#dipping from steed

Fix the reported bug of an unskilled rider who is unable to pick
items off the floor while mounted still being able to dip into water.
There might be other actions which need similar checking; this one only
handles the dip into pool/moat case.

src/pickup.c

@@ -1369,8 +1369,7 @@ int x, y;
 	if (!can_reach_floor()) {
 #ifdef STEED
 		if (u.usteed && P_SKILL(P_RIDING) < P_BASIC)
-			You("aren't skilled enough to reach from %s.",
-				mon_nam(u.usteed));
+			rider_cant_reach(); /* not skilled enough to reach */
 		else
 #endif
 			You("cannot reach the %s.", surface(x, y));