libc: krait: support KINGFISHER optimized memcpy

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

Change-Id: Idcfb94cc1e10d8326d7a9e623baed91125d7caf6
Merge branch 'kitkat' of github.com:AOSPAL/android_bionic into kitkat