am 661c21da: CameraService: Disconnect: Release mutex while waiting for joins.

    ALOGV("Camera %d: Waiting for threads", mCameraId);

    {

        // Don't wait with lock held, in case the other threads need to

        // complete callbacks that re-enter Camera2Client

        mBinderSerializationLock.unlock();

        mStreamingProcessor->join();

        mFrameProcessor->join();

        mCaptureSequencer->join();

        mZslProcessorThread->join();

        mCallbackProcessor->join();

        mBinderSerializationLock.lock();

    }

    ALOGV("Camera %d: Deleting streams", mCameraId);

    mStreamingProcessor->deletePreviewStream();