Merge "libbinder: only set sm stability if non-null" am: 7ac860e54f am: 99c72813ce am: cc45cabcba

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1536623

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: If71c9cecbdae738c588bb3e559b5ed380fe359bb