riding speed

While riding, your speed was calculated using the steeds speed only when
moving multi locations.  So, if you were walking step by step, it would use
your speed instead.  Changed this to use the steed's speed any time actual
movement occurs.

src/allmain.c

@@ -100,7 +100,7 @@ moveloop()
 
 		    /* calculate how much time passed. */
 #ifdef STEED
-		    if (u.usteed && flags.mv) {
+		    if (u.usteed && u.umoved) {
 			/* your speed doesn't augment steed's speed */
 			moveamt = mcalcmove(u.usteed);
 		    } else