[lldb/test] Skip TestCppIncompleteTypeMembers.py for -gmodules on macOS

Following 8b9caad, this only skips
TestCppIncompleteTypeMembers.py on macOS if we test with `-gmodules` enabled.

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/test/API/lang/cpp/incomplete-types/members/TestCppIncompleteTypeMembers.py

@@ -13,7 +13,7 @@ class TestCppIncompleteTypeMembers(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
 
-    @skipIfDarwin
+    @skipIf(oslist=['darwin','macos'], debug_info="gmodules")
     def test(self):
         self.build()
         lldbutil.run_to_source_breakpoint(self, "// break here",