arm: Implement VarHandle intrinsics for arrays.

Using benchmarks provided by
    https://android-review.googlesource.com/1420959
on blueline little cores with fixed frequency 1420800:
                      before after
GetArrayElementInt    28.252 0.021
GetArrayElementString 29.299 0.025
SetArrayElementInt    29.737 0.021
SetArrayElementString 32.842 0.025

Test: Covered by existing tests.
Test: testrunner.py --target --32 --optimizing
Bug: 71781600
Change-Id: I7a77696c33213b0c811be963acca3f61f5ed7593
1 file changed