Use bool for boolean in xselect.c, xsettings.c

* xselect.c (x_get_local_selection, struct selection_data)
(x_selection_request_lisp_error, struct prop_location)
(x_handle_selection_request, x_convert_selection)
(waiting_for_other_props_on_window, expect_property_change)
(wait_for_property_change, x_handle_property_notify)
(x_get_foreign_selection, x_get_window_property)
(receive_incremental_selection)
(x_get_window_property_as_lisp_data)
(lisp_data_to_selection_data, Fx_get_selection_internal)
(x_send_client_event):
* xselect.c, xterm.h (x_handle_dnd_message):
* xsettings.c (dpyinfo_valid, parse_settings, read_settings)
(apply_xft_settings, read_and_apply_settings)
(xft_settings_event, init_gsettings, init_xsettings)
(syms_of_xsettings):
Use bool for boolean.
* xselect.c (x_get_window_property): Omit last arg, which was an
unused boolean.
* xsettings.c (apply_xft_settings): Remove 2nd arg, which was
always true.  All callers changed.