[lldb] Run TestFrameLanguageCommands.py only on Darwin (llvm#141866)

Tests using ObjC do not readily run on Linux.

Author: kastiglione

lldb/test/API/commands/command/language/TestFrameLanguageCommands.py

@@ -5,6 +5,7 @@
 
 
 class TestCase(TestBase):
+    @skipUnlessDarwin
     def test(self):
         self.build()
         _, _, thread, _ = lldbutil.run_to_source_breakpoint(