Add automatic prefix handling to yasm functions. Does nothing now, but willbe useful for porting x264 asm in the future.
Originally committed as revision 16234 to svn://svn.ffmpeg.org/ffmpeg/trunk
split-radix FFTc is 1.9x faster than previous c (on various x86 cpus), sse is 1.6x faster than previous sse.
Originally committed as revision 14698 to svn://svn.ffmpeg.org/ffmpeg/trunk