libc: krait: support KINGFISHER optimized memcpy

When defined use the KINGFISHER optimized
cortex-a9 memcpy instead to improve performance.

Change-Id: Idcfb94cc1e10d8326d7a9e623baed91125d7caf6
Merge remote-tracking branch 'cyanogen/cm-11.0' into cm-11.0