Use ui_out_emit_table and ui_out_emit_list in print_thread_info_1

Use ui_out_emit_table and ui_out_emit_list in print_thread_info_1

This changes print_thread_info_1 to use ui_out_emit_table and
ui_out_emit_list.  Which one is used depends on whether the ui-out is
mi-like; so the emitters are wrapped in gdb::optional.

ChangeLog
2017-09-09  Tom Tromey  <tom@tromey.com>

	* thread.c (print_thread_info_1): Use ui_out_emit_table,
	ui_out_emit_list, gdb::optional.