camera2 ndk/vndk: cleanup->stop CameraDevice's looper in ~ACameraDevice()

It's possible that the following sequence happens:

1) hwbinder / binder thread T1: onResultReceived() starts -> promotes wp<CameraDevice> to sp<>;

2) Some other app thread T2 : ACameraDevice_close() -> delete ACameraDevice -> doesn't result in
                              CameraDevice's destructor running since mCameraDevice has another live
                              reference, app destroys some object O1.

3) T3 (callback looper thread): callback is received since looper is still running which accesses
                                dead app object O1 -> results in undefined behavior.

4) T1: onResultReceived completes and CameraDevice is destructed

We need to stop CameraDevice's looper thread (that waits for all callbacks queued to complete) in
~ACameraDevice() so we receive no callbacks after ACameraDevice is closed.

Bug: 135641415

Test: CTS native tests: no new failures
Test: AImageReaderVendorTest; enroll; while(1) auth;

Change-Id: Ia24de753f6ee409d941fff39616f09df2164880a
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>