Updates to the FFMPEG code, modernizing and improving

Make use of the check_c_source_compiles macro, added a check for
the renamed AVCodecId (was CodecId) and moved the test code to being
inline.

Change-Id: I699f51a9dec0452f4bc53c41bb143ecd777d5249
Merge topic 'ffmpeg-update' into master

5b39c918 Updates to the FFMPEG code, modernizing and improving