libc: Unbreak build for scorpion

Use cortex-a15 memcpy and krait memset routines

Change-Id: I02cb178b33b01fc91e903f1f7b620640fd0f3310
libc: krait: Implement optimized versions of memmove and bcopy

Restore a jellybean optimization for memmove and bcopy on krait.
Code has been refactored to thumb2 for consistency with the rest of
bionic libc, as well as performance and correctness.

Change-Id: I8f2f77dce4534fbce1bdf0188ab353bf34ab8637