libc: Fix memchr inclusion on scorpion

Change-Id: I0f4d31c85c8671be9790feab03469f89520763b7
libc: krait: Fix memmove half-word atomicity

In tailing case of less than 7, if even number of bytes are left, then
use half word load/store to make sure the whole routine is half-word
atomic

Change-Id: I54948ac050ff866986a7e144d4240652981ea87a