Merge "Add a null check in RTSPSource::stop" am: 2a692162a4 am: 40db8afe2a am: 371bfe9628 am: 932ca9fb41

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

Change-Id: I460e8d9160db16bf76e2b5b1c57c07e9536f4e29