eating an amulet of unchanging

Prompted by a suggestion on the newsgroup and from <Someone>, allow eating an
amulet of unchanging to remove intrinsic polymorph.

doc/fixes34.3

@@ -46,6 +46,7 @@ be more consistent with sounds when dropping into water
 surface() returns "bottom" when Underwater
 bill for all discarded, opened tins
 monsters that cannot pick things up cannot throw things either
+eating an amulet of unchanging removes intrinsic polymorph
 
 
 Platform- and/or Interface-Specific Fixes

src/eat.c

@@ -1542,6 +1542,13 @@ struct obj *otmp;
 		    flags.female ? "feminine" : "masculine");
 		context.botl = 1;
 		break;
+	    case AMULET_OF_UNCHANGING:
+		/* remove intrinsic polymorph only */
+		if (HPolymorph & INTRINSIC) {
+		    HPolymorph &= ~INTRINSIC;
+		    accessory_has_effect(otmp);
+		}
+		break;
 	    case AMULET_OF_STRANGULATION: /* bad idea! */
 		/* no message--this gives no permanent effect */
 		choke(otmp);
@@ -1552,7 +1559,6 @@ struct obj *otmp;
 		HSleeping = FROMOUTSIDE | rnd(100);
 		break;
 	    case RIN_SUSTAIN_ABILITY:
-	    case AMULET_OF_UNCHANGING:
 	    case AMULET_OF_LIFE_SAVING:
 	    case AMULET_OF_REFLECTION: /* nice try */
 	    /* can't eat Amulet of Yendor or fakes,