wishing for "<foo> of <bar> abilities" (trunk only)

wishing for "<foo> of <bar> abilities" (trunk only)

     Wishing for "{gain,restore,sustain} abilities" works since
makesingular() changes it to "* ability", but a post-3.4.3 change to
makesingular() caused "potion(s) of {gain,restore} abilities" and
"ring of sustain abilities" to fail to match the name, then yield a
random potion or ring.  If there turn out to be many other similar
situations, makesingular()'s behavior for "foo(s) of bars" may need
to revert.  For now, handle "* of * abilities" as a special case.