2-4% faster overall decode

Originally committed as revision 22896 to svn://svn.ffmpeg.org/ffmpeg/trunk

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

Originally committed as revision 15642 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 15630 to svn://svn.ffmpeg.org/ffmpeg/trunk

Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.'  to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".

Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 15118 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 13103 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 13102 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 10765 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 9486 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 9039 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 6670 to svn://svn.ffmpeg.org/ffmpeg/trunk

and fix GPL/LGPL version mismatches.

Originally committed as revision 6577 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 6219 to svn://svn.ffmpeg.org/ffmpeg/trunk

- Add new function av_tempfile() for creating temporary files; contains
  workaround for MinGW.
- Make XviD stuff use av_tempfile().

Originally committed as revision 5245 to svn://svn.ffmpeg.org/ffmpeg/trunk