Skip acquiring block-lock in BumpPointerSpace::AllocThreadUnsafe am: 6aa22c1284 am: b24bb40441 am: c9bca30be1 am: ace1a77a74 am: ba0cf6a1aa

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

Change-Id: I3c6c28bf686babaf0a662b8274e8160db4ad8262
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>