When attempting to re-enable the AltiVec support it was noticed
that we need to undefine _POSIX_C_SOURCE to appease the headers
for ff_get_cpu_flags_ppc() to be able to compile.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
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