Implement a SIMD spilling slot.

Rationale:
The last ART vectorizer break-out CL    \O/
This ensures spilling on x86 and x86_4 is correct.
Also, it paves the way to wider SIMD on ARM and MIPS.

Test: test-art-host
Bug: 34083438

Change-Id: I5b27d18c2045f3ab70b64c335423b3ff2a507ac2
6 files changed