Digestion attack can grant hero intrinsics

Monster purple worms can now gain intrinsics from swallowing foes whole,
so maybe the hero should be able to do so too.  Intrinsics aren't
granted immediately upon swallowing (that would probably have been
easier), but only once a corpse is created and then entirely digested.

I'm not sure if this is too powerful and was being avoided deliberately
for that reason, since it includes potential level gain from wraith
corpses in addition to other intrinsics.  That's consistent with monster
purple worms but may be a bit too much in the hands of the hero, though
it is limited by needing the corpse creation roll to succeed.

src/decl.c

@@ -674,6 +674,7 @@ const struct instance_globals g_init = {
 
     /* uhitm.c */
     FALSE, /* override_confirmation */
+    NON_PM, /* corpsenm_digested */
 
     /* vision.c */
     UNDEFINED_PTR, /* viz_array */

src/eat.c

@@ -3791,4 +3791,16 @@ Popeye(int threat)
     return FALSE;
 }
 
+/* the hero has swallowed a monster whole as a purple worm or similar, and has
+   finished digesting its corpse (called via g.afternmv) */
+int
+Finish_digestion(void)
+{
+    if (g.corpsenm_digested != NON_PM) {
+        cpostfx(g.corpsenm_digested);
+        g.corpsenm_digested = NON_PM;
+    }
+    return 0;
+}
+
 /*eat.c*/

src/uhitm.c

@@ -4462,8 +4462,9 @@ gulpum(struct monst *mdef, struct attack *mattk)
                         && !(g.mvitals[monsndx(pd)].mvflags & G_NOCORPSE)) {
                         /* nutrition only if there can be a corpse */
                         u.uhunger += (pd->cnutrit + 1) / 2;
-                    } else
+                    } else {
                         tmp = 0;
+                    }
                     Sprintf(msgbuf, "You totally digest %s.", mon_nam(mdef));
                     if (tmp != 0) {
                         /* setting afternmv = end_engulf is tempting,
@@ -4477,6 +4478,9 @@ gulpum(struct monst *mdef, struct attack *mattk)
                         nomul(-tmp);
                         g.multi_reason = "digesting something";
                         g.nomovemsg = msgbuf;
+                        /* possible intrinsic once totally digested */
+                        g.corpsenm_digested = monsndx(pd);
+                        g.afternmv = Finish_digestion;
                     } else
                         pline1(msgbuf);
                     if (pd == &mons[PM_GREEN_SLIME]) {