Previously, the code set itype=IT_POINT, then picked a closest point.
If the closest point was v0 or v1, itype stayed IT_POINT, otherwise it
became IT_EDGE. If itype==IT_POINT, then the function returns
(itype == IT_POINT) ? IT_NONE : itype;
=>
IT_NONE
for (dist <= rad). Otherwise, it returns IT_NONE. Short-circuit this
by returning IT_NONE without computing the distance.