Fix bug in vectorization of charAt, with regression test

Rationale:
String array get instruction cannot be vectorized
in a straightforward way, since compression has
to be dealt with. So rejected for now.

Test: test-art-target, test-art-host
Bug: 37151445
Change-Id: I16112cb8b1be30babd8ec07af5976db0369f8c28
2 files changed