libstagefright: enable smoothstreaming in ACodec

Enable smoothstreaming mode from ACodec
 - To handle stride change along with crop notification,
   notify NativeWindow with update-buffer-geometry
 - Enable smoothstreaming by-default based on the flag
   TARGET_ENABLE_DEFAULT_SMOOTHSTREAMING

Change-Id: I2a60035993f521fc164d3176d179882c6748b44e