Merge "Nullability check for mman module." am: b72900c5c9 am: ebd33d5977

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2580311

Change-Id: I93552a62eabb0464233ff53937ce9d9e04f22f81
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>