Empty range should iterate just once for inclusive and none for exclusive

just once:
while_rangex(u8).init(2, 2, true, 1);
while_rangex(u8).init(2, 2, true, -1);

none:
while_rangex(u8).init(2, 2, false, 1);
while_rangex(u8).init(2, 2, false, -1);