libc: x86: Use SSE2 or SSSE3 optimized routines when possible.

This patch uses the new hardware feature macros for x86 to define
various compile-time macros used to make the C library use
SSE2 and/or SSSE3 optimized memory functions for target CPUs
that support these features.

Note that previously, we relied on the macros being defined by
build/core/combo/, but this is no longer the

Change-Id: Ieae5ff5284c0c839bc920953fb6b91d2f2633afc
1 file changed