build: Cleanup CPU-specific optimizations

 * TARGET_ARCH_CPU_VARIANT was a Linaro thing. Now that Android
   introducted TARGET_CPU_VARIANT, we should use this instead.
 * Added CFLAGS for Krait and Scorpion after the cleanup.

Change-Id: Iafb40ecefa353a1169c22601be4ce80069c3f587
Change "cm-" prefix to "CyanKang-"

Change-Id: Ifb70f74767204d39ea19bac1f6b4c3499df50899
Merge branch 'cm-10.2' of github.com:CyanogenMod/android_build into working