This increases compatibilty with nasm and is also more consistent,
e.g. with h264_intrapred.asm and h264_chromamc.asm that already
do it that way.
Originally committed as revision 25042 to svn://svn.ffmpeg.org/ffmpeg/trunk
biweight code to sse2/ssse3; add sse2 weight code; and use that same code to
create mmx2 functions also, so that the inline asm in h264dsp_mmx.c can be
removed. OK'ed by Jason on IRC.
Originally committed as revision 25019 to svn://svn.ffmpeg.org/ffmpeg/trunk
