'A' again - avoid stale takeoff.mask

The do_wear.c part just eliminates some redundant code but shouldn't
produce any change in behavior.

The steal.c part should fix problems with 'A' when outer items are
taken off during theft in order to steal an inner item, where the
outer item is next to be removed (call to cancel_don() wasn't being
made).  The wield.c part matches the X_off() behavior and is needed
to handle a weapon item that's slated for removal but isn't next (so
wouldn't pass the donning()/doffing() test to trigger cancel_don()).

If this seems a lot like trial and error, it is....

src/do_wear.c

@@ -1,4 +1,4 @@
-/* NetHack 3.6	do_wear.c	$NHDT-Date: 1496547229 2017/06/04 03:33:49 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.96 $ */
+/* NetHack 3.6	do_wear.c	$NHDT-Date: 1496614914 2017/06/04 22:21:54 $  $NHDT-Branch: NetHack-3.6.0 $:$NHDT-Revision: 1.97 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -1200,53 +1200,30 @@ struct obj *obj; /* if null, do all worn items; otherwise just obj itself */
 }
 
 /* check whether the target object is currently being put on (or taken off--
-   also checks for doffing) */
+   also checks for doffing--[why?]) */
 boolean
 donning(otmp)
 struct obj *otmp;
 {
-    /* long what = (occupation == take_off) ? context.takeoff.what : 0L; */
-    long what = context.takeoff.what; /* if nonzero, occupation is implied */
     boolean result = FALSE;
 
     /* 'W' and 'T' set afternmv, 'A' sets context.takeoff.what */
-    if (otmp == uarm)
-        result = (afternmv == Armor_on || afternmv == Armor_off
-                  || what == WORN_ARMOR);
+    if (doffing(otmp))
+        result = TRUE;
+    else if (otmp == uarm)
+        result = (afternmv == Armor_on);
     else if (otmp == uarmu)
-        result = (afternmv == Shirt_on || afternmv == Shirt_off
-                  || what == WORN_SHIRT);
+        result = (afternmv == Shirt_on);
     else if (otmp == uarmc)
-        result = (afternmv == Cloak_on || afternmv == Cloak_off
-                  || what == WORN_CLOAK);
+        result = (afternmv == Cloak_on);
     else if (otmp == uarmf)
-        result = (afternmv == Boots_on || afternmv == Boots_off
-                  || what == WORN_BOOTS);
+        result = (afternmv == Boots_on);
     else if (otmp == uarmh)
-        result = (afternmv == Helmet_on || afternmv == Helmet_off
-                  || what == WORN_HELMET);
+        result = (afternmv == Helmet_on);
     else if (otmp == uarmg)
-        result = (afternmv == Gloves_on || afternmv == Gloves_off
-                  || what == WORN_GLOVES);
+        result = (afternmv == Gloves_on);
     else if (otmp == uarms)
-        result = (afternmv == Shield_on || afternmv == Shield_off
-                  || what == WORN_SHIELD);
-    /* these 1-turn items don't need 'afternmv' checks
-       [and may not actually need 'what' checks] */
-    else if (otmp == uamul)
-        result = (what == WORN_AMUL);
-    else if (otmp == uleft)
-        result = (what == LEFT_RING);
-    else if (otmp == uright)
-        result = (what == RIGHT_RING);
-    else if (otmp == ublindf)
-        result = (what == WORN_BLINDF);
-    else if (otmp == uwep)
-        result = (what == W_WEP);
-    else if (otmp == uswapwep)
-        result = (what == W_SWAPWEP);
-    else if (otmp == uquiver)
-        result = (what == W_QUIVER);
+        result = (afternmv == Shield_on);
 
     return result;
 }