* optimized avg_* functions (except xy2) * minor speedup for put_pixels_x2 & cleanup
* optimized avg_* functions (except xy2)
* minor speedup for put_pixels_x2 & cleanup


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@619 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg