Merge "Add a null check in RTSPSource::stop" am: 2a692162a4 am: 40db8afe2a am: 371bfe9628

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/1456267

Change-Id: I80c3abc3d9cd1a3cfa8760ff2986f401ae5cfcc8