Fix mismatched preprocessor comment.
diff --git a/asio/include/asio/execution_context.hpp b/asio/include/asio/execution_context.hpp
index d425d6e..0d91195 100644
--- a/asio/include/asio/execution_context.hpp
+++ b/asio/include/asio/execution_context.hpp
@@ -34,7 +34,7 @@
 template <typename Service> Service& use_service(io_context&);
 template <typename Service> void add_service(execution_context&, Service*);
 template <typename Service> bool has_service(execution_context&);
-#endif // !defined(ASIO_NO_DEPRECATED)
+#endif // !defined(GENERATING_DOCUMENTATION)
 
 namespace detail { class service_registry; }