CMake build fails on HTTP feauture disabled

[devingryu]

It seems that build fails on these options are set.

OP_DISABLE_HTTP=ON
OP_DISABLE_DOCS=ON

The following are error logs.

[1/2] Linking C executable opusfile_example
FAILED: opusfile_example 
: && /home/user/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --target=aarch64-none-linux-android24 --sysroot=/home/user/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/sysroot -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security  -O2 -g -DNDEBUG -Wl,--build-id=sha1 -Wl,--no-rosegment -Wl,--no-undefined-version -Wl,--fatal-warnings -Wl,--no-undefined -Qunused-arguments   -Wl,--gc-sections CMakeFiles/opusfile_example.dir/examples/opusfile_example.c.o -o opusfile_example  libopusfile.so  -lopusurl  /shared/aarch64/lib/libogg.so  /shared/aarch64/lib/libopus.so  -lm  -latomic -lm && :
ld.lld: error: unable to find library -lopusurl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[2/2] Linking C executable seeking_example
FAILED: seeking_example 
: && /home/user/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --target=aarch64-none-linux-android24 --sysroot=/home/user/android-ndk-r26c/toolchains/llvm/prebuilt/linux-x86_64/sysroot -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security  -O2 -g -DNDEBUG -Wl,--build-id=sha1 -Wl,--no-rosegment -Wl,--no-undefined-version -Wl,--fatal-warnings -Wl,--no-undefined -Qunused-arguments   -Wl,--gc-sections CMakeFiles/seeking_example.dir/examples/seeking_example.c.o -o seeking_example  libopusfile.so  -lopusurl  /shared/aarch64/lib/libogg.so  /shared/aarch64/lib/libopus.so  -lm  -latomic -lm && :
ld.lld: error: unable to find library -lopusurl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

The problem is clear: CMakeFiles.txt is set to link the opusurl when it builds the example. So setting OP_DISABLE_EXAMPLES=ON solves the issue.

I propose two solutions for this:

1. Splitting the example code into two, one that uses the network and one that doesn't.
2. Disable building examples on OP_DISABLE_HTTP=ON is set.

Thanks in advance.