message: [lit] Detect unexpected passes in lldbtest.
  This patch will have lit report unexpected passes when dotest reports at
  least one XPASS and no failures.
diff: @@ -96,6 +96,10 @@ class LLDBTest(TestFormat):
  if exitCode:
  return lit.Test.FAIL, out + err
  + unexpected_test_line = 'XPASS'
  + if unexpected_test_line in out or unexpected_test_line in err:
  + return lit.Test.XPASS, ''
  +
  passing_test_line = 'RESULT: PASSED'
  if passing_test_line not in out and passing_test_line not in err:
  msg = ('Unable to find %r in dotest output:\n\n%s%s' %
  