Backwards compatible download of apprtc to a new location. Bug: None Change-Id: Ida5e457dc37a29e37f5a590537ebf47470516213 Reviewed-on: https://webrtc-review.googlesource.com/c/webrtc.DEPS/+/151129 Reviewed-by: Patrik Höglund <phoglund@webrtc.org>