Shut down Email process when sync is totally blocked

* When sync threads get blocked by SSL/Socket code, we detect this
  and shutdown the ClientConnectionManager, hoping this will solve
  the problem.
* Apparently, this doesn't always work.  The result is that syncs
  are frozen until the device is rebooted (certainly) or until the
  Email process is stopped and restarted (hopefully)
* This CL kills the Email process after an unsuccessful attempt to
  clear blocked threads using ClientConnectionManager.shutdown()

Bug: 2615293
Change-Id: I8445b278817e508a855adeb88d6b2f969d28858b
1 file changed