Introduce tui_data_window::display_all_data method

Introduce tui_data_window::display_all_data method

This changes tui_display_all_data to be a method on tui_data_window.
This helps cluster uses of the TUI_DATA_WIN global.

gdb/ChangeLog
2019-07-17  Tom Tromey  <tom@tromey.com>

	* tui/tui-windata.h (tui_display_all_data): Don't declare.
	* tui/tui-windata.c (tui_data_window::display_all_data): Rename
	from tui_display_all_data.
	* tui/tui-win.c
	(tui_data_window::do_make_visible_with_new_height): Update.
	* tui/tui-regs.c (tui_show_registers): Update.
	* tui/tui-layout.c (tui_set_layout): Update.
	* tui/tui-data.h (struct tui_data_window) <display_all_data>: New
	method.