Actually call empty block visitor function

Author: virtuald

cxxheaderparser/parser.py

@@ -505,7 +505,8 @@ def _consume_static_assert(
     def _on_empty_block_start(
         self, tok: LexToken, doxygen: typing.Optional[str]
     ) -> None:
-        self._push_state(EmptyBlockState)
+        state = self._push_state(EmptyBlockState)
+        self.visitor.on_empty_block_start(state)
 
     def _on_block_end(self, tok: LexToken, doxygen: typing.Optional[str]) -> None:
         old_state = self._pop_state()