hero infravision

Take a first step towards making the mons[] array be readonly.
The only other place that updates it is when changing succubus and
incubus AD_SSEX attacks to AD_SEDU ones and that can be handled
via existing getmattk(), but so far has proven to be trickier than
anticipated.

src/role.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	role.c	$NHDT-Date: 1546137492 2018/12/30 02:38:12 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.55 $ */
+/* NetHack 3.6	role.c	$NHDT-Date: 1547086250 2019/01/10 02:10:50 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.56 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985-1999. */
 /*-Copyright (c) Robert Patrick Rankin, 2012. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -2098,6 +2098,14 @@ role_init()
     /* 0 or 1; no gods are neuter, nor is gender randomized */
     quest_status.godgend = !strcmpi(align_gtitle(alignmnt), "goddess");
 
+#if 0
+/*
+ * Disable this fixup so that mons[] can be const.  The only
+ * place where it actually matters for the hero is in set_uasmon()
+ * and that can use mons[race] rather than mons[role] for this
+ * particular property.  Despite the comment, it is checked--where
+ * needed--via instrinsic 'Infravision' which set_uasmon() manages.
+ */
     /* Fix up infravision */
     if (mons[urace.malenum].mflags3 & M3_INFRAVISION) {
         /* although an infravision intrinsic is possible, infravision
@@ -2113,6 +2121,7 @@ role_init()
         if (urole.femalenum != NON_PM)
             mons[urole.femalenum].mflags3 |= M3_INFRAVISION;
     }
+#endif /*0*/
 
     /* Artifacts are fixed in hack_artifacts() */