Trivial UI change in libwnck

[Elijah Newren <newren gmail com>]

I finally applied the patch in
http://bugzilla.gnome.org/show_bug.cgi?id=124463, which  makes window
list tooltips from the Window List applet on the panel display the
WM_NAME instead of WM_ICON_NAME.  Probably not noticable to most users
and probably not something documented, I'm guessing.  :)