Fix H.264 interframe decoding when compiling with icc. Patch by Loren
"It seems that icc copies the constants from their global var onto the
stack, at which point they're not aligned, hence the crash.
[This change] really shouldn't mean anything different, but maybe it'll
confuse icc into not performing that 'optimization'."
Originally committed as revision 12772 to svn://svn.ffmpeg.org/ffmpeg/trunk