Remove tui_alloc_win_info

Remove tui_alloc_win_info

There is only a single caller of tui_alloc_win_info, and we're going
to add more "new" cases to that caller, so remove tui_alloc_win_info
and inline it into init_and_make_win.

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

	* tui/tui-data.h (tui_alloc_win_info): Don't declare.
	* tui/tui-layout.c (init_and_make_win): Use "new" directly.
	* tui/tui-data.c (tui_alloc_win_info): Remove.