Merge "Nullability check for signalfd module" am: 0a9fd0e77e

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2482936

Change-Id: I039ff3af8bb3bb8d601a193a76d896b44c1e6fbe
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>