unless it stands for ffmpeg the program or is historic

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

This cleanup patch updates the developer documentation with respect to
the migration to the git scm.

Originally committed as revision 25364 to svn://svn.ffmpeg.org/ffmpeg/trunk

- mention clobber-marking of xmm registers,
- some notes on external vs. inline asm, including tips on which to use for
   what situation and to not rewrite+improve in the same patch (as with C code)
- some more best-practice guidelines

See "[PATCH] update doc/optimization.txt" thread on ML.

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It contains optimizations that are not specific to i386 and
libavutil uses this naming scheme already.

Originally committed as revision 16270 to svn://svn.ffmpeg.org/ffmpeg/trunk

Neither the asm() nor the __asm__() keyword is part of the C99
standard, but while GCC accepts the former in C89 syntax, it is not
accepted in C99 unless GNU extensions are turned on (with -fasm). The
latter form is accepted in any syntax as an extension (without
requiring further command-line options).

Sun Studio C99 compiler also does not accept asm() while accepting
__asm__(), albeit reporting warnings that it's not valid C99 syntax.

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can allso be used as a torture test for ur spelling checker

Originally committed as revision 1444 to svn://svn.ffmpeg.org/ffmpeg/trunk