vf_scale.h & related cleanup & some small warning fix by dominik

git-svn-id: file:///var/local/repositories/mplayer/trunk/postproc@10234 b3059339-0415-0410-9bf9-f77b7e298cf2

rgb2rgb.h

@@ -127,4 +127,6 @@ static void yuv2rgb_init (unsigned bpp, int mode){
 printf("broken, this should use the swscaler\n");
 }
 
+void sws_rgb2rgb_init(int flags);
+
 #endif