MLP DSP functions x86-optimized.
12.59% overall speedup in x86_32
 9.98% overall speedup in x86_64
compared to gcc 4.3.3

It breaks on x86_64 with PIC because the MANGLE macro appends (%%rip), which
is not wanted for labels.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@18904 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b