Add standard method for enabling mfpu and mcpu code optimization
build: move bionic optimizations to NEON makefile

Change-Id: Idd495ddbb49f67fef5496456803263f8a23643c5
 build: Relax Cortex CFLAGS

* Always set march=armv7-a
 * Use mtune instead of mcpu. Bad code is generated on A15 otherwise.

Change-Id: I946df7e146de9be9aa590fe50f5eb655616c4e05
use 4.7 instead

Change-Id: Iaa589eb6634321f0550631d3c1a37dd5468a6202