Change tui_update_breakpoint_info to be a method

Change tui_update_breakpoint_info to be a method

This changes tui_update_breakpoint_info to be a method on
tui_source_window_base.

gdb/ChangeLog
2019-08-16  Tom Tromey  <tom@tromey.com>

	* tui/tui-winsource.h (struct tui_source_window_base)
	<update_breakpoint_info>: Declare.
	(tui_update_breakpoint_info): Don't declare.
	* tui/tui-winsource.c (tui_source_window_base::update_source_window_as_is)
	(tui_update_all_breakpoint_info): Update.
	(tui_source_window_base::update_breakpoint_info): Rename from
	tui_update_breakpoint_info.
	(tui_source_window_base::update_exec_info): Update.