Correct bug#65919

Correct bug#65919

* src/process.c (child_signal_notify): Expunge call to
non-reentrant function from signal handler.

* src/xfns.c (setup_xi_event_mask): Cease selecting for
XI_FocusIn and XI_FocusOut under X toolkit builds.

* src/xterm.c (xi_handle_interaction, xi_handle_focus_change)
(xi_handle_focus_change): Make conditional on GTK 3 or no
toolkit builds.
(xi_handle_delete_frame, x_free_frame_resources): Adjust
correspondingly.
(handle_one_xevent) <EnterNotify, LeaveNotify>: Examine
EnterNotify and LeaveNotify events for focus changes
irrespective of whether XI2 is enabled under the X toolkit and
GTK 2.x.