This eliminates all aliasing violation warnings in h264 code.
No measurable speed difference with gcc-4.4.3 on i7.
Originally committed as revision 21881 to svn://svn.ffmpeg.org/ffmpeg/trunk
Thats not possible except maybe in FMO which noone uses anyway.
iam also not sure if this wasnt missing a part_width.
Originally committed as revision 21312 to svn://svn.ffmpeg.org/ffmpeg/trunk