ignition-common and gazebo bottles broken by ffmpeg version 4

[scpeters]

ffmpeg version 4 got merged in Homebrew/homebrew-core#26882 and it's broken the ignition-common and gazebo bottles:

• https://build.osrfoundation.org/view/os_homebrew/job/gazebo-install-one_liner-homebrew-amd64/886/console
• https://build.osrfoundation.org/view/os_homebrew/job/ignition_common-ci-ign-common1-homebrew-amd64/9/console

We need to fix the compilation errors and rebuild the bottles

ign-common/src/Video.cc:167:29:
 error: use of undeclared identifier 'CODEC_CAP_TRUNCATED'
  if (codec->capabilities & CODEC_CAP_TRUNCATED)
                            ^
ign-common/src/Video.cc:168:39:
 error: use of undeclared identifier 'CODEC_FLAG_TRUNCATED'
    this->dataPtr->codecCtx->flags |= CODEC_FLAG_TRUNCATED;
                                      ^
2 errors generated.

[scpeters]

I think the symbol is now called AV_CODEC_CAP_TRUNCATED

[scpeters]

fixed by #405