Merge commit '78fa0b9033c0834c049e2aedf71a8c613fed87ab'

* commit '78fa0b9033c0834c049e2aedf71a8c613fed87ab':
  h264_metadata: Always add the SEI user data to the first access unit

Mostly already present from a308872b049e33f69f4b629a06f47e3681906b93,
one cosmetic change applied.

Merged-by: Mark Thompson <sw@jkqxz.net>

diff --cc libavcodec/h264_metadata_bsf.c
Simple merge