bug#36165: 27.0.50; `select-frame-set-input-focus' moves mouse pointer outside of frame

[martin rudalics]

> In emacs -Q, disable scroll-bar-mode and evaluate:
>
> (let ((mouse-autoselect-window t))
>    (select-frame-set-input-focus (window-frame)))
>
> The mouse pointer will now be to the right of the window frame; with
> normal window managers, this doesn't matter much, except that a "resize
> this window" cursor might be shown rather than the usual one, but with
> tiling window managers, the cursor position may correspond to another
> window, which is then raised and wrongly receives keyboard focus. This
> actually happened to me.
>
> The attached patch fixes things, by moving the mouse pointer to the last
> valid x position.

Pushed to master.  Please have a look and close the bug in case I did
things right.

Thank your very much, martin