ART: Implement predicated SIMD vectorization.

This CL brings support for predicated execution for
auto-vectorizer and implements arm64 SVE vector backend.

This version passes all the VIXL simulator-runnable tests in
SVE mode with checker off (as all VecOp CHECKs need to be
adjusted for an extra input) and all tests in NEON mode.

Test: art SIMD tests on VIXL simulator.
Test: art tests on FVP (steps in test/README.arm_fvp.md)

Change-Id: Ib78bde31a15e6713d875d6668ad4458f5519605f
13 files changed