gdb/tui: remove special handling of locator/status window

gdb/tui: remove special handling of locator/status window

The locator window, or status window as it is sometimes called is
handled differently to all the other windows.

The reason for this is that the class representing this
window (tui_locator_window) does two jobs, first this class represents
a window just like any other that has space on the screen and fills
the space with content.  The second job is that this class serves as a
storage area to hold information about the current location that the
TUI windows represent, so the class has members like 'addr' and
'line_no', for example which are used within this class, and others
when they want to know which line/address the TUI windows should be
showing to the user.

Because of this dual purpose we must always have an instance of the
tui_locator_window so that there is somewhere to store this location
information.

The result of this is that the locator window must never be deleted
like other windows, which results in some special case code.

In this patch I propose splitting the two roles of the
tui_locator_window class.  The tui_locator_window class will retain
just its window drawing parts, and will be treated just like any other
window.  This should allow all special case code for this window to be
deleted.

The other role, that of tracking the current tui location will be
moved into a new class (tui_location_tracker), of which there will be
a single global instance.  All of the places where we previously use
the locator window to get location information will now be updated to
get this from the tui_location_tracker.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* Makefile.in (SUBDIR_TUI_SRCS): Add tui/tui-location.c.
	(HFILES_NO_SRCDIR): Add tui/tui-location.h.
	* tui/tui-data.h (TUI_STATUS_WIN): Define.
	(tui_locator_win_info_ptr): Delete declaration.
	* tui/tui-disasm.c: Add 'tui/tui-location.h' include.
	(tui_disasm_window::set_contents): Fetch state from tui_location
	global.
	(tui_get_begin_asm_address): Likewise.
	* tui/tui-layout.c (tui_apply_current_layout): Remove special case
	for locator window.
	(get_locator_window): Delete.
	(initialize_known_windows): Treat locator window just like all the
	rest.
	* tui/tui-source.c: Add 'tui/tui-location.h' include.
	(tui_source_window::set_contents): Fetch state from tui_location
	global.
	(tui_source_window::showing_source_p): Likewise.
	* tui/tui-stack.c: Add 'tui/tui-location.h' include.
	(_locator): Delete.
	(tui_locator_win_info_ptr): Delete.
	(tui_locator_window::make_status_line): Fetch state from
	tui_location global.
	(tui_locator_window::rerender): Remove check of 'handle',
	reindent function body.
	(tui_locator_window::set_locator_fullname): Delete.
	(tui_locator_window::set_locator_info): Delete.
	(tui_update_locator_fullname): Delete.
	(tui_show_frame_info): Likewise.
	(tui_show_locator_content): Access window through TUI_STATUS_WIN.
	* tui/tui-stack.h (tui_locator_window::set_locator_info): Moved to
	tui/tui-location.h and renamed to
	tui_location_tracker::set_location.
	(tui_locator_window::set_locator_fullname): Moved to
	tui/tui-location.h and renamed to
	tui_location_tracker::set_fullname.
	(tui_locator_window::full_name): Delete.
	(tui_locator_window::proc_name): Delete.
	(tui_locator_window::line_no): Delete.
	(tui_locator_window::addr): Delete.
	(tui_locator_window::gdbarch): Delete.
	(tui_update_locator_fullname): Delete declaration.
	* tui/tui-wingeneral.c (tui_refresh_all): Removed special handling
	for locator window.
	* tui/tui-winsource.c: Add 'tui/tui-location.h' include.
	(tui_display_main): Call function on tui_location directly.
	* tui/tui.h (enum tui_win_type): Add STATUS_WIN.
	* tui/tui-location.c: New file.
	* tui/tui-location.h: New file.