media: Don't wait at MediaRecorder::stop() if we haven't received any frames.

Also add a maximum stopTimeOffset in MediaCodecSource to guard against long delay
in MediaSource which leads to MediaRecorder::stop() getting stuck.

Bug:62629994
Test: MediaRecorder CTS test.

Change-Id: Ic58f295c9be1b1f500324261be6a34f322ef518e
2 files changed