message: Add logging to TestQueues.py
  In an attempt to understand why the test is still failing after r355555,
  add some logging.
diff: @@ -56,7 +56,23 @@ class TestQueues(TestBase):
  expected_running,
  (queue.GetNumRunningItems())))
  + def describe_threads(self):
  + desc = []
  + for x in self.inferior_process:
  + id = x.GetIndexID()
  + reason_str = lldbutil.stop_reason_to_str(x.GetStopReason())
  +
  + location = "\t".join([lldbutil.get_description(
  + x.GetFrameAtIndex(i)) for i in range(x.GetNumFrames())])
  + desc.append(
  + "thread %d: %s at\n\t%s" %
  + (id, reason_str, location))
  + print('\n'.join(desc))
  +
  def check_number_of_threads_owned_by_queue(self, queue, number_threads):
  + if (queue.GetNumThreads() != number_threads):
  + self.describe_threads()
  +
  self.assertTrue(
  queue.GetNumThreads() == number_threads,
  "queue %s should have %d thread executing, but has %d" %
  @@ -125,6 +141,8 @@ class TestQueues(TestBase):
  if len(threads) != 1:
  self.fail("Failed to stop at breakpoint 1.")
  + self.inferior_process = process
  +
  queue_submittor_1 = lldb.SBQueue()
  queue_performer_1 = lldb.SBQueue()
  queue_performer_2 = lldb.SBQueue()
  @@ -291,6 +309,8 @@ class TestQueues(TestBase):
  if len(threads) != 1:
  self.fail("Failed to stop at breakpoint 1.")
  + self.inferior_process = process
  +
  libbtr_module_filespec = lldb.SBFileSpec("libBacktraceRecording.dylib")
  libbtr_module = target.FindModule(libbtr_module_filespec)
  if not libbtr_module.IsValid():
  