libc: Unbreak build for scorpion

Use cortex-a15 memcpy and krait memset routines

Change-Id: I02cb178b33b01fc91e903f1f7b620640fd0f3310
libc: Fix memchr inclusion on scorpion

Change-Id: I0f4d31c85c8671be9790feab03469f89520763b7