fixes entry for pull-req #643 - historic statues

monstone() was using a hardcoded value when flagging the statue of
a unique monster as historic and didn't get updated when the corpse
and statue flags kept in obj->spe were changed last June by commit
04a8ddcce1.

Closes #643

src/mon.c

@@ -2696,6 +2696,7 @@ monstone(struct monst* mdef)
     if ((int) mdef->data->msize > MZ_TINY
         || !rn2(2 + ((int) (mdef->data->geno & G_FREQ) > 2))) {
         unsigned corpstatflags = CORPSTAT_NONE;
+
         oldminvent = 0;
         /* some objects may end up outside the statue */
         while ((obj = mdef->minvent) != 0) {