Allow same-length integral type mixing in SIMD.

Rationale:
Just like the incoming sequential code, the SIMD
code allows for some type matching, as long as
it is integral and same length.

Bug: 37764324
Test: test-art-target, test-art-host
Change-Id: Ide1c5403e0f3b8c5372e8ac6dd282d8211ca8f1b