Fix xwidgets with XInput 2 builds

Fix xwidgets with XInput 2 builds

* src/xwidget.c (Fmake_xwidget): Refrain from synthesizing
a focus event here on XI2 builds.
(Fxwidget_perform_lispy_event): Try to set embedder on XI2
builds and do nothing otherwise.
(synthesize_focus_in_event): Use focus_change.window as opposed
to any.window.
(x_draw_xwidget_glyph_string): Synthesize focus event here
instead on XI2 builds.