Disable TestAArch64UnwindPAC.py for non PAC targets

TestAArch64UnwindPAC.py started failing on LLDB buildbot as underlying
hardware does not support PAC. This patch skips this test for targets
which do not support PAC feature.

lldb/test/API/functionalities/unwind/aarch64_unwind_pac/TestAArch64UnwindPAC.py

@@ -15,6 +15,9 @@ class AArch64UnwindPAC(TestBase):
     @skipIf(oslist=no_match(['linux']))
     def test(self):
         """Test that we can backtrace correctly when AArch64 PAC is enabled"""
+        if not self.isAArch64PAuth():
+            self.skipTest('Target must support Pointer Authentication.')
+
         self.build()
 
         self.line = line_number('main.c', '// Frame func_c')