stagefright: Those who cannot remember history are doomed to repeat it

 * A new sniffer might want to defer it's work based on the
   knowledge already gained by those who have already sniffed.
 * This is the case for our FFMPEG sniffer, which is pretty awesome
   in that it is able to fill in all the gaps and detect almost
   anything, however the cost is additional latency during scanning
   and startup.
 * As we cycle thru each sniffer, feed the current score to the next.
   It is up to the extractor to use this knowledge wisely.
 * Additionally, print some metrics on how long the sniff took.

Change-Id: I5dc8de11ed4939a01eabb0cae0b4e1e71d991eea