Bump GTK+ required version to 2.11
Bump GTK+ required version to 2.11

libunique now requires gtk+ 2.11/2.12 for the gtk_window_set_startup_id()
function, which changes the startup notification id on a window.

Distrotech/libunique,GNOME/unique,GNOME/unique,GNOME/unique,Distrotech/libunique,Distrotech/libunique