[RFA]: Make gdb_do_one_event public and fix uiout setting for TUI

[Stephane Carrez]

Hi!

Elena Zannoni wrote:

>
> 
> I am not sure I understand this change, can you comment a bit?
> 
>       a init_ui_hook.  */
> -  uiout = cli_out_new (gdb_stdout);
> +  tui_old_uiout = uiout = cli_out_new (gdb_stdout);
> 


When we start gdb without -tui, the 'tui_old_uiout' was not
set because 'tui_enable/tui_disable' are not called.  This is because
we are initializing gdb and thus there are no hooks to remove (ie no
need to and must not call tui_disable).

Later on in the tui loop, the 'tui_old_uiout' is used to re-initialize
'uiout' (since we are not in TUI mode).

	Stephane