Merge "Nullability check for wchar module." am: 182cebf612

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2519858

Change-Id: I64ff0e209c192667bdddd89aec59232bb79953cd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>