Skip TestLibCxxAtomic with gcc

older versions of libc++ (still used on some linux systems) are not
compatible with gcc.

llvm-svn: 300837

lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libcxx/atomic/TestLibCxxAtomic.py

@@ -23,6 +23,7 @@ class LibCxxAtomicTestCase(TestBase):
         var.SetPreferSyntheticValue(True)
         return var
 
+    @skipIf(compiler=["gcc"])
     @add_test_categories(["libc++"])
     def test(self):
         """Test that std::atomic as defined by libc++ is correctly printed by LLDB"""