SEDUCE=0

When SEDUCE is disabled, instead of swapping attacks in mons[] once,
do it on the fly in getmattk() whenever needed.  That allows mons[]
to become readonly, although this doesn't declare it 'const' because
doing so will require a zillion 'struct permonst *' updates to match.

This seemed trickier than it should be, but that turned out to be
because the old behavior was broken.  Setting SEDUCE=0 in sysconf or
user's own configuration file resulted in all succubus and incubus
attacks being described as monster smiles engagingly or seductively
rather than hitting (while dishing out physical damage).  I didn't
try rebuilding 3.4.3 to see whether this was already broken before
being migrated to SYSCF.

src/sys.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	sys.c	$NHDT-Date: 1448241785 2015/11/23 01:23:05 $  $NHDT-Branch: master $:$NHDT-Revision: 1.35 $ */
+/* NetHack 3.6	sys.c	$NHDT-Date: 1547118632 2019/01/10 11:10:32 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.43 $ */
 /* Copyright (c) Kenneth Lorber, Kensington, Maryland, 2008. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -120,13 +120,17 @@ sysopt_release()
     return;
 }
 
-extern struct attack sa_yes[NATTK];
-extern struct attack sa_no[NATTK];
+extern const struct attack sa_yes[NATTK];
+extern const struct attack sa_no[NATTK];
 
 void
 sysopt_seduce_set(val)
 int val;
 {
+#if 0
+/*
+ * Attack substitution is now done on the fly in getmattk(mhitu.c).
+ */
     struct attack *setval = val ? sa_yes : sa_no;
     int x;
 
@@ -134,6 +138,9 @@ int val;
         mons[PM_INCUBUS].mattk[x] = setval[x];
         mons[PM_SUCCUBUS].mattk[x] = setval[x];
     }
+#else
+    nhUse(val);
+#endif /*0*/
     return;
 }