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
PPC is normally big endian but has special little endian load/store
instructions. Using these avoids a separate byteswap. This makes the
vorbis decoder about 5% faster. Not much else uses little-endian
read/write extensively.
GCC generates horrible PPC code for the default AV_[RW]B64 (which uses
a packed struct), so we override it with a plain pointer cast.
Originally committed as revision 18602 to svn://svn.ffmpeg.org/ffmpeg/trunk
