message: fix a typo in decorator
diff: @@ -120,7 +120,7 @@ class MiInterpreterExecTestCase(lldbmi_testcase.MiTestCaseBase):
  @skipIfFreeBSD # llvm.org/pr22411: Failure presumably due to known thread races
  @skipIfRemote # We do not currently support remote debugging via the MI.
  @skipIfDarwin
  - @SkipIfLinux
  + @skipIfLinux
  def test_lldbmi_thread_step_in(self):
  """Test that 'lldb-mi --interpreter' can step in by "thread step-in" command."""
  