Contribs: libpostproc was removed from libav

(cherry picked from commit 59c0cf6f)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/ffmpeg/rules.mak

@@ -12,7 +12,6 @@ FFMPEGCONF = \
 	--enable-libopenjpeg \
 	--disable-debug \
 	--enable-gpl \
-	--enable-postproc \
 	--disable-avdevice \
 	--disable-devices \
 	--disable-protocols \