Merge "Add FLAG_IMMUTABLE to PendingIntents" am: 78f856db7f

Original change: https://android-review.googlesource.com/c/platform/packages/apps/BasicSmsReceiver/+/2229419

Change-Id: I7005f35b3b302f5d2c15fc42f08caa30543e8c17
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>