Add missing multiple inclusion guards; clean up #endif comments;
add missing library prefixes; keep guard names consistent.

The Atom has SSSE3 support, which is useful in many cases, but sometimes the
SSSE3 version is slower than the SSE2 equivalent on the Atom, but is generally
faster on other processors supporting SSSE3. This flag allows for selectively
disabling certain SSSE3 functions on the Atom.

Signed-off-by: Mans Rullgard <mans@mansr.com>

This adds configure and runtime checks for AVX support on x86 CPUs.

Signed-off-by: Mans Rullgard <mans@mansr.com>

Instead of defining functions in per-arch header files included
by the main cpu.c, define them normally and call them from the
generic one.

Originally committed as revision 25084 to svn://svn.ffmpeg.org/ffmpeg/trunk

function and rename it to av_get_cpu_flags().

Originally committed as revision 25076 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 25047 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 25046 to svn://svn.ffmpeg.org/ffmpeg/trunk

symbols, and move them from libavcodec/avcodec.h to libavutil/cpu.h.

Originally committed as revision 25040 to svn://svn.ffmpeg.org/ffmpeg/trunk