Merge "Nullability check for system_properties module." am: 83f9b28792

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2593054

Change-Id: I7da1dec1bcb6b83c9c2629118a38387f91ee6ef0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>