add helper struct to modify global output_level within a scope

Debug/DebConfig.hh

@@ -80,6 +80,14 @@ private:
   Config& operator=(const Config&);
 };
 
+/// Helper struct to locally set the global output level and reset it when leaving the scope
+struct ScopedOutputLevel
+{
+  ScopedOutputLevel(int level) : lvl_bfre_(Config::query().output_level) { Config::modify().output_level = level; }
+  ~ScopedOutputLevel() { Config::modify().output_level = lvl_bfre_; }
+  int lvl_bfre_;
+};
+
 }; // namespace Debug
 
 #endif // DEB_ON