SensorService fixes

  i) Significant Motion multiple clients fix. Make a copy of
  mActiveConnections vector before cleaning up SensorEventConnections
  when one-shot sensors trigger.
  ii) Maintain a mapping between flush_complete_events and
  SensorEventConnections to accurately map flush() API calls and
  corresponding flush_complete_events
  iii) Remove all references to 1_1 and 1_2 HALs.
  iv) Dynamically allocate sensor_event buffers in SensorService main
  threadLoop.

Bug: 17412359
Change-Id: If3c3986197660cafef2d2e0b4dc7582e229cf1c4