Have g_queue_remove() return a boolean

Have g_queue_remove() return a boolean

g_queue_remove() should return a boolean so callers can verify that an
element was found and removed, as in the following example:

    if (g_queue_remove (queue, referenced_object))
        g_object_unref (referenced_object);

Similarly, g_queue_remove_all() should return the number of elements
found and removed.

https://bugzilla.gnome.org/show_bug.cgi?id=632294