Mentioned instructions introduced in ARMv6/ARMv7

Enable usage of ffs function in dlmalloc

Change-Id: I1bc10672b1d388475f82ff43da7c48df47ab70fe
include <machine/cpu-features.h> in byteorder.h

Without including cpu-features.h, __ARM_ARCH__ is undefined.

Change-Id: Ie1e005a4263dfa55364f03d95449dc52516c5987
Integrate Linaro Thumb-2 strlen implementation.

cherry-picked from Linaro cortex-strings r112

http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/changes

Change-Id: I35e6cc2caf39ac9b2d8cdba3f378988b2c71fac7
Signed-off-by: Rob Beane <robbeane@gmail.com>