Unable to read h264 video on PiZero with C++ static build

[crackwitz]

@jeanchristophe

--       avresample:                NO

this is the only component of ffmpeg that failed.

@jeanchristophe

CMake Warning at cmake/OpenCVUtils.cmake:876 (message):
  ocv_check_modules(FFMPEG): can't find library 'mmal_core'.  Specify
  'pkgcfg_lib_FFMPEG_mmal_core' manually

this is the place in your log where trouble starts (for ffmpeg). I can’t make heads or tails of it.