remove unneeded check

comparing nsides_ here isn't needed becasue nsides_ cannot change inside
that loop.

src/server/game.cpp

@@ -1074,7 +1074,7 @@ bool game::end_turn() {
 		turn_ended = true;
 	}
 	// Skip over empty sides.
-	for (int i = 0; i < nsides_ && nsides_ <= gamemap::MAX_PLAYERS && side_controllers_[current_side()] == "null"; ++i) {
+	for (int i = 0; i < nsides_ && side_controllers_[current_side()] == "null"; ++i) {
 		++end_turn_;
 		if (current_side() == 0) {
 			turn_ended = true;