[cherry-pick] Added decoding of IOCOM's IG2 H.264 non-standard H.264 streams - payload type 107 - identified as H264_IOCOM.

Note: VIC will decode IOCOM's 'standard H.264' [RFC3984] (the checkbox in the
video properties of IG2 needs to be checked) with latest ffmpeg library (when
patched to allow for use of one reference frame - when num_ref_frames=0 in SPS).
IOCOM will decode VIC's H.264 streams.

- Source: cherry-pick 0d095ff from mpeg4 branch