fix githib issue #179 - random drawbridge state

Fixes #179

The Valkyrie goal level has two drawbridges and one of them was set to
have 50:50 chance to be closed (raised).  But 'random' for drawbridge
open/closed (or lowered/raised) state was always choosing open (lowered).
This fixes that and also changes that level to have the old settings
(southern open, northern 50:50) for 75% of the time and new settings
(both 50:50) for 25% of the time.  So there's now a 12.5% chance that
both will be closed instead of both always being open (due to the bug
with handling random).

dat/Valkyrie.des

@@ -1,4 +1,4 @@
-# NetHack 3.6	Valkyrie.des	$NHDT-Date: 1432512783 2015/05/25 00:13:03 $  $NHDT-Branch: master $:$NHDT-Revision: 1.13 $
+# NetHack 3.6	Valkyrie.des	$NHDT-Date: 1553787633 2019/03/28 15:40:33 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.14 $
 #	Copyright (c) 1989 by Jean-Christophe Collet
 #	Copyright (c) 1991-2 by M. Stephenson
 # NetHack may be freely redistributed.  See license for details.
@@ -216,9 +216,13 @@ REGION:(00,00,34,16),lit,"ordinary"
 STAIR:(45,10),up
 # Non diggable walls
 NON_DIGGABLE:(00,00,34,16)
-# Drawbridges
+# Drawbridges; northern one opens to the south, southern one to the north
 DRAWBRIDGE:(17,02),south,random
-DRAWBRIDGE:(17,14),north,open
+IF [75%] {
+   DRAWBRIDGE:(17,14),north,open
+} ELSE {
+   DRAWBRIDGE:(17,14),north,random
+}
 # Objects
 OBJECT:('(',"crystal ball"),(17,08),blessed,5,name:"The Orb of Fate"
 OBJECT:random,random