ffmpeg: fix target_os deduction for embedded platform

[LevWi]

Specify library name and version: ffmpeg/4.4

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• [+] I've read the contributing guidelines.
• [+] I've used a recent Conan client version close to the currently deployed.
• [+] I've tried at least one configuration locally with the conan-center hook activated.

[CLAassistant]

All committers have signed the CLA.

[github-actions]

🤖 Beep Boop! This pull request is making changes to 'recipes/ffmpeg//'.

👋 @MartinDelille you might be interested. 😉

[ghost]

I detected other pull requests that are modifying ffmpeg/all recipe:

• [ffmpeg/5.1] Version bump #15830
• ffmpeg: conan v2 support #15819
• ffmpeg: conan v2 #15818
• ffmpeg: add strip argument to fix cross compilation issues #15459
• [ffmpeg] Modernize #15035

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[uilianries]

@LevWi Thank you for your hotfix. Please, write a comment on the PR #4 so the CI bot can add you to the access request list. Otherwise, your PR will not run by the CI.

[LevWi]

Hello @uilianries
Done: #4 (comment)
But nothing happen

[MartinDelille]

Maybe close and reopen the PR ?

[prince-chrismc]

You need to wait for the next PR to get merged with your name

[prince-chrismc]

The bot didn't rebuild this despite being approved

[prince-chrismc]

I opened an issue for the team to investigate :) I am pretty sure that it used to be automatic

[prince-chrismc]

You'll need to re approve after a merge commit, save it for when there's merge conflicts 🙏

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 4 (fa673d0b9ddfd24c89630c33d88822a36cefec17):

• ffmpeg/4.3.2@:
  All packages built successfully! (All logs)

• ffmpeg/4.4.3@:
  All packages built successfully! (All logs)

• ffmpeg/5.0@:
  All packages built successfully! (All logs)

• ffmpeg/4.2.1@:
  All packages built successfully! (All logs)

• ffmpeg/4.4@:
  All packages built successfully! (All logs)

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Conan v2 pipeline (informative, not required for merge) ❌

Note: Conan v2 builds are informative and they are not required for the PR to be merged.

The v2 pipeline failed. Please, review the errors and note this will be required for pull requests to be merged in the near future.

See details:

Failure in build 7 (fa673d0b9ddfd24c89630c33d88822a36cefec17):

• ffmpeg/5.0@:
  Error running command conan export --name ffmpeg --version 5.0 recipes/ffmpeg/all/conanfile.py:

  ERROR: Error loading conanfile at '/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py': Unable to load conanfile in /home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py", line 7, in <module>
      from conans import AutoToolsBuildEnvironment, tools
  ImportError: cannot import name 'AutoToolsBuildEnvironment' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)
  

• ffmpeg/4.4.3@:
  Error running command conan export --name ffmpeg --version 4.4.3 recipes/ffmpeg/all/conanfile.py:

  ERROR: Error loading conanfile at '/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py': Unable to load conanfile in /home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py", line 7, in <module>
      from conans import AutoToolsBuildEnvironment, tools
  ImportError: cannot import name 'AutoToolsBuildEnvironment' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)
  

• ffmpeg/4.4@:
  Error running command conan export --name ffmpeg --version 4.4 recipes/ffmpeg/all/conanfile.py:

  ERROR: Error loading conanfile at '/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py': Unable to load conanfile in /home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py", line 7, in <module>
      from conans import AutoToolsBuildEnvironment, tools
  ImportError: cannot import name 'AutoToolsBuildEnvironment' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)
  

• ffmpeg/4.3.2@:
  Error running command conan export --name ffmpeg --version 4.3.2 recipes/ffmpeg/all/conanfile.py:

  ERROR: Error loading conanfile at '/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py': Unable to load conanfile in /home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py", line 7, in <module>
      from conans import AutoToolsBuildEnvironment, tools
  ImportError: cannot import name 'AutoToolsBuildEnvironment' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)
  

• ffmpeg/4.2.1@:
  Error running command conan export --name ffmpeg --version 4.2.1 recipes/ffmpeg/all/conanfile.py:

  ERROR: Error loading conanfile at '/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py': Unable to load conanfile in /home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py
    File "<frozen importlib._bootstrap_external>", line 728, in exec_module
    File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
    File "/home/conan/w/prod-v2_cci_PR-15777/recipes/ffmpeg/all/conanfile.py", line 7, in <module>
      from conans import AutoToolsBuildEnvironment, tools
  ImportError: cannot import name 'AutoToolsBuildEnvironment' from 'conans' (/opt/pyenv/versions/3.7.13/lib/python3.7/site-packages/conans/__init__.py)
  

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[github-actions]

Hooks produced the following warnings for commit fa673d0

ffmpeg/5.0

post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavcodec.so' links to system library 'mvec' but it is not in cpp_info.system_libs.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavfilter.8.24.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavformat.59.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libpostproc.56.3.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswscale.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavutil.57.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavdevice.59.4.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswresample.4.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libpostproc.56.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswscale.6.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswscale.6.4.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavformat.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavutil.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavutil.57.17.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavcodec.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavcodec.59.18.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswresample.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavcodec.59.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavformat.59.16.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavdevice.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libpostproc.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavfilter.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavdevice.59.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libswresample.4.3.100.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.
post_package(): WARN: [MISSING SYSTEM LIBS (KB-H043)] Library './lib/libavfilter.8.dylib' links to system library 'CoreServices' but it is not in cpp_info.frameworks.