x11: Set GdkToplevelX11.have_focused on creation

x11: Set GdkToplevelX11.have_focused on creation

Since the order in which _NET_WM_STATE and _NET_WM_DESKTOP are set, or
even *if* they are set, isn't defined, we could end up unsetting
GDK_WINDOW_STATE_FOCUSED given that both handlers for these two X
properties end up doing window state changes for all states. As we
want GDK_WINDOW_STATE_FOCUSED to be set by default we need to set its
master flag by default as well.

https://bugzilla.gnome.org/show_bug.cgi?id=673125