Move source window common to code to tui-winsource.[ch]

Move source window common to code to tui-winsource.[ch]

Like the previous rearranging patches, this moves the source and
disassembly window base class code to tui-winsource.[ch].  The
execution info window is also moved, because it is associated with
this base class.

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

	* tui/tui-winsource.h (struct tui_exec_info_window)
	(struct tui_source_window_base): Move from tui-data.h.
	* tui/tui-winsource.c: Move many method definitions from
	elsewhere.  Remove "structuring" comments.
	* tui/tui-wingeneral.c (tui_source_window_base::make_visible)
	(tui_source_window_base::refresh_window): Move to
	tui-winsource.c.
	* tui/tui-win.c (tui_source_window_base::refresh_all)
	(tui_source_window_base::update_tab_width)
	(tui_source_window_base::set_new_height)
	(tui_source_window_base::do_make_visible_with_new_height): Move to
	tui-winsource.c.
	* tui/tui-source.h: Update.
	* tui/tui-source.c (tui_source_window_base::reset): Move to
	tui-winsource.c.
	* tui/tui-disasm.h: Update.
	* tui/tui-data.h (struct tui_exec_info_window): Move to
	tui-winsource.h.
	(struct tui_source_window_base): Likewise.
	* tui/tui-data.c (tui_source_window_base::clear_detail)
	(tui_source_window_base, ~tui_source_window_base): Move to
	tui-winsource.c.