AWindow: check if surfacetexture already exists
The SurfaceTextureListener attached to the TextureView won't be signalled if the SurfaceTexture already exists and is already bound to the TextureView. It means that a call to attachTextureView() will never end to the expected call to setSurface(), blocking the playback in this situation.
Pointed-out-by: Aleksandra Krzemień
Fixes #1587 (closed)