refine blocked levitation/flight (trunk only)

Levitation side-effects get skipped if Levitation toggles while it
is blocked, so BFlying (the reason Flying is blocked) could become stale
in some situations.  Enlightment feedback about latent flight capability
was the only thing affected.

src/hack.c

@@ -543,6 +543,9 @@ dosinkfall()
 	    off_msg(obj);
 	}
 	HLevitation--;
+	/* probably moot; we're either still levitating or went
+	   through float_down(), but make sure BFlying is up to date */
+	float_vs_flight();
 }
 #endif
 
@@ -1665,9 +1668,7 @@ switch_terrain()
 	BFlying |= FROMOUTSIDE;
     } else if (BFlying) {
 	BFlying &= ~FROMOUTSIDE;
-	/* in case BFlying got set due to levitation which then went away
-	   while blocked; there'd be no float_down() with reset of BFlying */
-	if (!HLevitation && !ELevitation) BFlying &= ~I_SPECIAL;
+	float_vs_flight();	/* maybe toggle (BFlying & I_SPECIAL) */
 	/* [minor bug: we don't know whether this is beginning flight or
 	   resuming it; that could be tracked so that this message could
 	   be adjusted to "resume flying", but isn't worth the effort...] */