[ffmpeg] enable opengl feature on osx

[mcmtroffaes]

• What does your PR fix?

  The opengl feature was disabled on osx when compiling ffmpeg[all], however ffmpeg supports it perfectly on osx and it compiles with no problems (see for instance https://github.com/mcmtroffaes/ffmpeg-msvc-build/runs/2903919175).

• Which triplets are supported/not supported? Have you updated the CI baseline?

  No changes besides adding an extra feature for osx.

• Does your PR follow the maintainer guide?

  Yes.

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  Yes.

[NancyLi1013]

Hi @mcmtroffaes

Thanks again for your PR.

Building package ffmpeg[all,all-gpl,all-nonfree,ass,avcodec,avdevice,avfilter,avformat,avresample,bzip2,core,fdk-aac,fontconfig,freetype,fribidi,gpl,iconv,ilbc,lzma,modplug,mp3lame,nonfree,opencl,opengl,openh264,openjpeg,openssl,opus,postproc,snappy,soxr,speex,swresample,swscale,theora,vorbis,vpx,webp,x264,x265,zlib]:x64-osx...
CMake Error at ports/ffmpeg/portfile.cmake:76 (message):
  Feature 'opengl' does not support 'uwp | (windows & arm) | osx'
Call Stack (most recent call first):
  scripts/ports.cmake:139 (include)

Seems this is still needed to update.

vcpkg/ports/ffmpeg/portfile.cmake

Lines 75 to 76 in 6e024e7

	if (((VCPKG_TARGET_ARCHITECTURE STREQUAL "arm" OR VCPKG_TARGET_ARCHITECTURE STREQUAL "arm64") AND VCPKG_TARGET_IS_WINDOWS) OR VCPKG_TARGET_IS_UWP OR VCPKG_TARGET_IS_OSX)
	message(FATAL_ERROR "Feature 'opengl' does not support 'uwp | (windows & arm) | osx'")

[mcmtroffaes]

Oh yes, I missed it as I removed these checks in my CI to allow testing the more experimental features. Fixed now.

[NancyLi1013]

You should have tested this feature opengl on osx, right?

[mcmtroffaes]

You should have tested this feature opengl on osx, right?

Well, I don't have a mac myself for in-depth testing, however I've run a simple test application on CI https://github.com/mcmtroffaes/ffmpeg-msvc-build/runs/2903919175#step:14:1122 which shows that the opengl device can be opened on osx.

[NancyLi1013]

The feature opengl has passed on x64-osx on my local machine.

Building package ffmpeg[avcodec,avdevice,avfilter,avformat,core,gpl,opengl,postproc,swresample,swscale]:x64-osx... done
Installing package ffmpeg[avcodec,avdevice,avfilter,avformat,core,gpl,opengl,postproc,swresample,swscale]:x64-osx...
Installing package ffmpeg[avcodec,avdevice,avfilter,avformat,core,gpl,opengl,postproc,swresample,swscale]:x64-osx... done
Elapsed time for package ffmpeg:x64-osx: 5.426 min

Thanks again for your efforts @mcmtroffaes.

[mcmtroffaes]

You're welcome, and thanks for running an extra local test. I'm pretty confident that if it works on CI it should also work for users but better be safe than sorry!

[mcmtroffaes]

Merged master & bumped port version again.

[BillyONeal]

Thanks for your contribution!