Fix thread-safety-analysis warning on Clang r484197 am: 788d46a488 am: 3a8dbbc3f7

Original change: https://android-review.googlesource.com/c/platform/art/+/2385813

Change-Id: I65ae6138a7afd11a4fcc4d183a1a7575ab291885
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>