Fixes for collections.Counter (#159368)

Pull Request resolved: https://github.com/pytorch/pytorch/pull/159368
Approved by: https://github.com/mlazos
ghstack dependencies: #159365, #159366

torch/_dynamo/variables/builtin.py

@@ -2543,6 +2543,13 @@ class BuiltinVariable(VariableTracker):
                 (operator.neg)(a.as_proxy()),
                 sym_num=None,
             )
+
+        if (
+            isinstance(a, UserDefinedObjectVariable)
+            and a.call_obj_hasattr(tx, "__neg__").value  # type: ignore[attr-defined]
+        ):
+            return a.call_method(tx, "__neg__", [], {})
+
         # None no-ops this handler and lets the driving function proceed
         return None