Merge "Nullability check for stdlib  module." am: 6a65763b12

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2618672

Change-Id: Iad181f09a2249c69711ae3051a499924d38c8e19
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>