goa-auth-handler: pass the data pointer to auth_cb
goa-auth-handler: pass the data pointer to auth_cb

We are supposed to use it in this callback, if only to free it, so we should
really pass it as user_data.

https://bugzilla.gnome.org/show_bug.cgi?id=680952

GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets