Get initial thread state coordinator integration working.

* Fixed bug in run loop where run loop return enum was being treated
  erroneously like an int, causing the TSC event loop to terminate
  prematurely.

* Added an explicit scope in NativeProcessLinux::Resume() for the
  threads lock lifetime.  (This was likely unnecessary but is
  more explicit.)

* Fixed a bug in ThreadStateCoordinator where resume execution was
  not updating the internal state about the thread assumed to be
  running now.  I'll add a test and upstream this in a moment.

* Added a verbose logging mechanism to event processing within
  ThreadStateCoordinator.  It is currently enabled when the
  'log enable lldb thread' is true upon inferior launch/attach.

llvm-svn: 227909