Add gradfun filter, ported from MPlayer.
Patch by Nolan L nol888 <=> gmail >=< com.
See thread:Subject: [FFmpeg-devel] [PATCH] Port gradfun to libavfilter (GCI)Date: Mon, 29 Nov 2010 07:18:14 -0500
Originally committed as revision 25942 to svn://svn.ffmpeg.org/ffmpeg/trunk
use a Makefile in x86 subdir
Originally committed as revision 25234 to svn://svn.ffmpeg.org/ffmpeg/trunk