libwnck pager (2.31.0) has been extended with a versioning api and
a layout policy mechanism. This makes our aspect ratio hack for
pager in a deskbar mode unnecessary.

The modified libwnck version is currently available at:
http://git.gnome.org/browse/libwnck/log/?h=wip/xfce-4.10-fixes
(cherry picked from commit 77c3ac772ec79f3a8020d86db26b7583fd2a9223)