SensorService fixes.

   1) Flush should only be received by the app calling flush(). Maintain
      a queue of all flush() calls and send flush_complete events in that
      order.
   2) Log warnings for older HALs. Remove batch() calls with DRY_RUN flag.
   3) Reallocate event cache when more sensors register and the desired
      maxCacheSize increases. Clear NEEDS_ACK flag in the buffer whenever
      there is a write() failure.
   4) More dump information. Add wake-up flag, maxDelay and timestamps for
      sensor events.

Bug: 16874778
Change-Id: I195646191059fd31f75f2f07886c0f98bf9b509a