Separate out locator window

Separate out locator window

This introduces a new subclass of tui_gen_win_info for the locator,
letting us remove another element from union tui_which_element.

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

	* tui/tui-wingeneral.c (tui_refresh_all): Update.
	* tui/tui-win.c (tui_resize_all, tui_adjust_win_heights)
	(tui_source_window_base::set_new_height): Update.
	* tui/tui-stack.c (tui_make_status_line): Change parameter type.
	Update.
	(tui_set_locator_fullname, tui_set_locator_info)
	(tui_show_frame_info): Update.
	* tui/tui-source.c (tui_set_source_content)
	(tui_source_is_displayed): Update.
	* tui/tui-layout.c (show_source_disasm_command, show_data)
	(show_source_or_disasm_and_command): Update.
	* tui/tui-disasm.c (tui_set_disassem_content)
	(tui_get_begin_asm_address): Update.
	* tui/tui-data.h (struct tui_locator_element): Remove.
	(union tui_which_element) <locator>: Remove.
	(struct tui_locator_window): New.
	(tui_locator_win_info_ptr): Change return type.
	* tui/tui-data.c (_locator): Change type.
	(tui_locator_win_info_ptr): Change return type.
	(init_content_element): Remove LOCATOR_WIN case.  Add assert.
	(tui_alloc_content): Add assert.