Bug#905595: qtwebengine-opensource-src: libav* build-dependencies should be (>= 7:3.3.2)

[Andreas Ferber <af+debian-bugregports@chaos-agency.de>]

Source: qtwebengine-opensource-src
Version: 5.11.1+dfsg-5
Severity: normal

Hi,

when trying to build the package on stretch (with various backports), it
fails with the following error:

--------------
../../3rdparty/chromium/media/ffmpeg/ffmpeg_common.cc: In function 'media::VideoCodec media::CodecIDToVideoCodec(AVCodecID)':
../../3rdparty/chromium/media/ffmpeg/ffmpeg_common.cc:192:10: error: 'AV_CODEC_ID_AV1' was not declared in this scope
     case AV_CODEC_ID_AV1:
          ^~~~~~~~~~~~~~~
../../3rdparty/chromium/media/ffmpeg/ffmpeg_common.cc: In function 'AVCodecID media::VideoCodecToCodecID(media::VideoCodec)':
../../3rdparty/chromium/media/ffmpeg/ffmpeg_common.cc:217:14: error: 'AV_CODEC_ID_AV1' was not declared in this scope
       return AV_CODEC_ID_AV1;
              ^~~~~~~~~~~~~~~
--------------

Looking at the git history of the ffmpeg debian package showed that the
first version containing the missing definition is version 7:3.3.2-1,
even though the FFmpeg upstream changelog itself first mentions AV1
support for version 4.0. This seems to be somewhat confirmed by the fact
that building against the FFmpeg packages from deb-multimedia.org (based
on FFmpeg 3.3.8) works.

Therefore I think the build-dependencies on libavcodec-dev,
libavformat-dev and libavutil-dev should be bumped to (>= 7:3.3.2)

Regards,
Andreas Ferber