pixdesc: rename PIX_FMT_* flags to AV_PIX_FMT_FLAG_*
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  pixdesc: rename PIX_FMT_* flags to AV_PIX_FMT_FLAG_*

Conflicts:
	doc/APIchanges
	libavcodec/avpicture.c
	libavcodec/ffv1dec.c
	libavcodec/ffv1enc.c
	libavcodec/imgconvert.c
	libavcodec/tiffenc.c
	libavfilter/vf_pixdesctest.c
	libavfilter/vf_scale.c
	libavutil/imgutils.c
	libavutil/pixdesc.c
	libavutil/version.h
	libswscale/swscale_internal.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Reduce probing score for flic animation files.

Fixes ticket #2567.