RFC: Make string/memory functions optimized for unaligned SSE2 as default

[H.J. Lu]

The current default string/memory functions for x86-64 in libc and ld.so were
implemented before SSE is allowed in ld.so and unaligned SSE load/store
is faster on most processors.  Today, we can use the same string/memory
functions in libc and ld.so, most of x86-64 processors have fast unaligned
SSE load/store.  We should update the default string/memory functions for
x864-64 to unaligned SSE2 version.  Those functions are

memcpy-sse2-unaligned.S   strcat-sse2-unaligned.S  strncat-sse2-unaligned.S
stpcpy-sse2-unaligned.S   strcmp-sse2-unaligned.S  strncpy-sse2-unaligned.S
stpncpy-sse2-unaligned.S  strcpy-sse2-unaligned.S  strstr-sse2-unaligned.S

We should make them the default in libc and ld.so.

Any comments?


-- 
H.J.