Fix DCHECK()s in read barrier slow paths.

This is a follow-up to
    https://android-review.googlesource.com/1478798
to fix non-Baker read barrier configurations.

Test: ART_READ_BARRIER_TYPE=TABLELOOKUP m test-art-host-gtest
Bug: 170286013
Change-Id: I6044d4fba720e0ed11b254990021f5b8236964a3
3 files changed