Skip acquiring block-lock in BumpPointerSpace::AllocThreadUnsafe am: 6aa22c1284 am: b24bb40441 am: c9bca30be1 am: ace1a77a74

Original change: https://android-review.googlesource.com/c/platform/art/+/2183095

Change-Id: I1b5ff55b6d9d6e2958a4b1965082ed2584787fd4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>