Merge "Nullability check for execinfo module" am: e87938c435

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2386455

Change-Id: If149a33bc4fe4b13b83f63c865f0d91da54a81ff
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>