hwaccel: Simplify ff_find_hwaccel

It is always called by passing fields from an AVCodecContext.
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  hwaccel: Simplify ff_find_hwaccel

Conflicts:
	libavcodec/mpeg12dec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/fade: add color option.

Fixes Ticket #1822.
avfilter/fade: use inlink->frame_count.
avfilter/fade: remove a bunch of useless parenthesis.
avfilter/fade: use FADE_OUT macro.
ffmpeg: remove unneeded include "libswscale/swscale.h"

Found-by: ramiro
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>