tidy up gamma-based brightness #93

	name: CI
	on: [ push, pull_request, workflow_dispatch ]

	jobs:
	build-linux:
	name: Linux polymost=${{ matrix.use_polymost }} gl=${{ matrix.use_opengl }} nogtk=${{ matrix.without_gtk \|\| 1 }}
	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	matrix:
	use_polymost: [ 0, 1 ]
	use_opengl: [ 0, 1 ]
	exclude:
	- use_polymost: 1
	use_opengl: 0
	include:
	- use_polymost: 1
	use_opengl: 3
	- use_polymost: 1
	use_opengl: 'USE_GLES2'
	without_gtk: '0'

	steps:
	- name: Checkout code
	uses: actions/checkout@v3
	- name: Install dependencies
	run: \|
	sudo apt-get update
	sudo apt-get install -y libsdl2-dev libgtk-3-dev
	- name: Make
	run: \|
	cd "$GITHUB_WORKSPACE"
	make USE_POLYMOST=${{ matrix.use_polymost }} \
	USE_OPENGL=${{ matrix.use_opengl }} \
	WITHOUT_GTK=${{ matrix.without_gtk \|\| 1 }} \
	USE_ASM=0 \
	all

	build-windows:
	name: Windows polymost=${{ matrix.use_polymost }} gl=${{ matrix.use_opengl }}
	runs-on: windows-latest
	strategy:
	fail-fast: false
	matrix:
	use_polymost: [ 0, 1 ]
	use_opengl: [ 0, 1 ]
	exclude:
	- use_polymost: 1
	use_opengl: 0
	include:
	- use_polymost: 1
	use_opengl: 3

	steps:
	- name: Checkout code
	uses: actions/checkout@v3
	- name: Setup MSVC
	uses: ilammy/msvc-dev-cmd@v1
	with:
	sdk: 10.0.19041.0
	- name: Add XAudio2 redistributable
	run: vcpkg install xaudio2redist:x64-windows
	- name: Make
	shell: cmd
	run: \|
	echo USE_POLYMOST=${{ matrix.use_polymost }} > Makefile.msvcuser
	echo USE_OPENGL=${{ matrix.use_opengl }} >> Makefile.msvcuser
	echo VCPKG_ROOT=%VCPKG_INSTALLATION_ROOT% > kenbuild\Makefile.msvcuser
	nmake /f Makefile.msvc all

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