sacrificing tune-up (trunk only)

There was code to give feedback if you attempted to offer the Amulet
on a regular altar instead of the final high altar, but that code was
unreachable; getobj() yielded "that's a silly thing" whenever you picked
an amulet while not on the Astral (or recently changed, Sanctum) level.
This allows you to try to offer the real or fake Amulet of Yendor on any
altar, but they'll only be listed as likely candidates when on the Astral
level.  Conversely, it no longer lists carried corpses as likely candidates
at the Astral high altars; they're still acceptable but not what the hero
is supposed to be fiddling with there.  Also, allow corpses on the floor
to be offered on high altars, fixing a complaint we've gotten a few times
over the years.  (Unfortunately there's no way to suppress them as likely
candidates on the high altars while still allowing them to be sacrified.)

src/invent.c

@@ -925,9 +925,12 @@ register const char *let,*word;
 		|| (!strncmp(word, "rub on the stone", 16) &&
 		    *let == GEM_CLASS &&
 		    otmp->dknown && objects[otyp].oc_name_known)
-		|| (!strcmp(word, "sacrifice") && Is_sanctum(&u.uz) &&
-		    (otyp == AMULET_OF_YENDOR || otyp == FAKE_AMULET_OF_YENDOR))
+		/* suppress corpses on astral, amulets elsewhere */
+		|| (!strcmp(word, "sacrifice") &&
+		    /* (!astral && amulet) || (astral && !amulet) */
+		    (!Is_astralevel(&u.uz) ^ otmp->oclass != AMULET_CLASS))
 		    ) {
+			/* acceptable but not listed as likely candidate */
 			foo--;
 			allowall = TRUE;
 			*ap++ = otmp->invlet;