Use emplace() instead of insert() where applicable for maps.

Source/Core/VideoCommon/OnScreenDisplay.cpp

@@ -71,7 +71,7 @@ void ClearMessages()
 // On-Screen Display Callbacks
 void AddCallback(CallbackType type, Callback cb)
 {
-	s_callbacks.insert(std::pair<CallbackType, Callback>(type, cb));
+	s_callbacks.emplace(type, cb);
 }
 
 void DoCallbacks(CallbackType type)