ffmpeg @5.x: buildbot failures for 10.9 through 10.11

[mascguy (Christopher Nielsen)]

For this new release of FFMpeg, buildbot builds are failing with two different compilation errors.

​https://ports.macports.org/port/ffmpeg-devel/builds/

For 10.11, the failure relates to __builtin_available:

libavutil/hwcontext_videotoolbox.c:420:13: error: use of unknown builtin '__builtin_available' [-Wimplicit-function-declaration]
        if (__builtin_available(macOS 10.11, iOS 9, *))
            ^

However, for 10.9 and 10.10, we're seeing the following:

libavcodec/videotoolbox.c:907:13: error: implicit declaration of function 'VTRegisterProfessionalVideoWorkflowVideoDecoders' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
            VTRegisterProfessionalVideoWorkflowVideoDecoders();
            ^

Upstream included the following patch in the 5.0 release, and initially that appeared - at least superficially - like it should fix these issues. But unfortunately that's not the case. (Might be a simple matter of tweaking the preprocessor logic, though.)

​https://www.mail-archive.com/ffmpeg-devel@ffmpeg.org/msg128213.html

[mascguy (Christopher Nielsen)]

FYI for anyone interested: This issue is a blocker, preventing us from updating the non-Devel port to 5.0.

[Christopher Nielsen <mascguy@…>]

In 0f6d11daecb8e8c6bd6673703a3417cd1f660a1d/macports-ports (master):

ffmpeg-devel: patch for builtin_available failures
See: #64469

[mascguy (Christopher Nielsen)]

Latest patch gets us further along, but failures still seen for 10.9 through 10.11. More digging needed...

[Christopher Nielsen <mascguy@…>]

In 4d5e70321a481dc3a712e04f12a9e1d46157071f/macports-ports (master):

ffmpeg-upstream: fix builds for 10.9 thru 10.11
Fixes: #64469