Fix over-allocation of DexCache field array.

Fix a facepalm in DexCacheArraysLayout that causes
over-allocation of the DexCache fields array.
We should not waste valuable flash storage and
virtual address space with all these zeros.

Total boot*.art size for aosp_angler-userdebug:
  - arm:
    - before: 13316096
    - after: 11603968 (1.6MiB, -13%)
  - arm64:
    - before: 9486336
    - after: 8626176 (-0.8MiB, 9%)
We should have saved half of this with the original
change rather than regressing the other half.

Test: m test-art-host-gtest
Test: testrunner.py --host --interp-ac
Test: testtunner.py --host --interpreter
Bug: 30627598
Change-Id: Ied2ffc4fc8e569141fd6db45841163f7f071ddd0
2 files changed