Merge "Nullability check for xattr module." am: 0f371ff845 am: ace1448647

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2597870

Change-Id: I04fc42d8074446aa7b059afe74bad5738347e330
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>