InputCommon: Fix memory leak in ExpressionParser

We allocate in MakeSuppressor via `return unique_ptr(std::make_unique<...>(...).release(), InvokingDeleter{}`, so it wasn't properly getting freed.

Source/Core/InputCommon/ControlReference/ExpressionParser.cpp

@@ -37,6 +37,7 @@ public:
     void operator()(T* func)
     {
       (*func)();
+      delete func;
     }
   };