Fix: mon_hates_material and player race

mon_hates_material(mondata.c) was not evaluating the hero's race
correctly due to upstream changes in 580c5a6, which removed the attempt
to assess the hero's race from is_elf, is_dwarf, etc macros (for reasons
described in that commit message).  However, mon_hates_material was
just passing gy.permonst.data to hates_material and relying on those
macros to include the hero's race in the equation, so it was no longer
working properly for an unpolymorphed hero after those changes.  Make it
explicitly check material hatred of the hero's race if not polymorphed.

I had to remove the 'const' qualifier on raceptr to use it here, because
keeping it would have led to a cascading requirement to add 'const' on
all sorts of other functions (hates_material -> dmgtype ->
dmgtype_fromattack...) -- and those really _should_ have const
parameters, but I think that would have to be an upstream change to
avoid risking a bunch of merge conflicts in subsequent merges.

include/extern.h

@@ -1770,7 +1770,7 @@ extern const char *locomotion(const struct permonst *, const char *);
 extern const char *stagger(const struct permonst *, const char *);
 extern const char *on_fire(struct permonst *, struct attack *);
 extern const char *msummon_environ(struct permonst *, const char **);
-extern const struct permonst *raceptr(struct monst *);
+extern struct permonst *raceptr(struct monst *);
 extern boolean olfaction(struct permonst *);
 extern int monmaterial(int);
 extern int emits_light(struct permonst *);

src/mondata.c

@@ -458,7 +458,7 @@ mstrength_ranged_attk(register struct permonst* ptr)
 boolean
 mon_hates_material(struct monst *mon, int material)
 {
-    if (hates_material(mon->data, material))
+    if (hates_material(raceptr(mon), material))
         return TRUE;
 
     /* extra case: shapeshifted vampires still hate silver */
@@ -1367,8 +1367,8 @@ big_little_match(int montyp1, int montyp2)
  * Returns correct pointer for non-polymorphed and polymorphed
  * player.  It does not return a pointer to player role character.
  */
-const struct permonst *
-raceptr(struct monst* mtmp)
+struct permonst *
+raceptr(struct monst *mtmp)
 {
     if (mtmp == &gy.youmonst && !Upolyd)
         return &mons[gu.urace.mnum];