Fix "auxiliary" typo

Fix "auxiliary" typo

The TUI has a function called tui_win_is_auxillary, but the word
should actually be spelled "auxiliary".  This fixes the typo.

gdb/ChangeLog
2019-06-25  Tom Tromey  <tom@tromey.com>

	* tui/tui-wingeneral.c (tui_gen_win_info::make_visible): Update.
	* tui/tui-win.c (make_invisible_and_set_new_height): Update.
	* tui/tui-layout.c (init_and_make_win): Update.
	* tui/tui.h (enum tui_win_type): Update.
	* tui/tui-data.h (tui_win_is_auxiliary): Rename from
	tui_win_is_auxillary.
	* tui/tui-data.c (tui_win_is_auxiliary): Rename from
	tui_win_is_auxillary.