Merge "Nullability check for wait module." am: e1df179f00

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2539233

Change-Id: I7c301238386a530fc9e51babd898f1553e597636
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>