Game::loadcustomlevelstats: move some declarations to later in function

The declarations of `std::vector<std::string> customlevelnames` and
`std::vector<int> customlevelscores` are made quite early in the
function, commented with "Old system", but the place where the old
system is processed is after a big chunk of code that processes the new
system (and indeed never uses these vectors). So for readability,
they're now closer to where they're used.

desktop_version/src/Game.cpp

@@ -504,10 +504,6 @@ void Game::loadcustomlevelstats(void)
 
     customlevelstats.clear();
 
-    // Old system
-    std::vector<std::string> customlevelnames;
-    std::vector<int> customlevelscores;
-
     tinyxml2::XMLElement* pElem;
     tinyxml2::XMLElement* firstElement;
 
@@ -553,6 +549,9 @@ void Game::loadcustomlevelstats(void)
 
 
     // Since we're still here, we must be on the old system
+    std::vector<std::string> customlevelnames;
+    std::vector<int> customlevelscores;
+
     for (pElem = firstElement; pElem; pElem=pElem->NextSiblingElement())
     {
         const char* pKey = pElem->Value();