Remove set but not used variables

Highlighted by clang-15 warnings such as:

warning: variable 'index' set but not used [-Wunused-but-set-variable]

Source/Modules/lua.cxx

@@ -1418,7 +1418,6 @@ public:
     List *baselist = Getattr(n, "bases");
     if (baselist && Len(baselist)) {
       Iterator b;
-      int index = 0;
       b = First(baselist);
       while (b.item) {
 	String *bname = Getattr(b.item, "name");
@@ -1431,7 +1430,6 @@ public:
 	Printf(base_class_names, "\"%s *\",", SwigType_namestr(bname));
 
 	b = Next(b);
-	index++;
       }
     }
     // First, print class static part