Merge commit '7716dd9f'

* commit '7716dd9f':
  xvid: switch to xvid mmx idct as soon as possible

Conflicts:
	libavcodec/mpeg4videodec.c

Not merged, as the bug was not merged either

See: 6c9b82b6, and related commits
Merged-by: Michael Niedermayer <michaelni@gmx.at>