Instruction set features for ARM64, MIPS and X86.

Also, refactor how feature strings are handled so they are additive or
subtractive.
Make MIPS have features for FPU 32-bit and MIPS v2. Use in the quick compiler
rather than #ifdefs that wouldn't have worked in cross-compilation.
Add SIMD features for x86/x86-64 proposed in:
  https://android-review.googlesource.com/#/c/112370/

Bug: 18056890

Change-Id: Ic88ff84a714926bd277beb74a430c5c7d5ed7666
69 files changed