Codechange: replace strnatcmp with C++ string capable version

src/group_gui.cpp

@@ -191,7 +191,7 @@ private:
 				GetString(last_name[1], STR_GROUP_NAME, lastof(last_name[1]));
 			}
 
-			int r = strnatcmp(last_name[0], last_name[1]); // Sort by name (natural sorting).
+			int r = StrNaturalCompare(last_name[0], last_name[1]); // Sort by name (natural sorting).
 			if (r == 0) return a->index < b->index;
 			return r < 0;
 		});