Remove explicit XNFocusWindow

XCreateIC ICValues default XNFocusWindow to XNClientWindow if not
specified, it can be omitted since it is the same.

From the documentation
https://www.x.org/releases/current/doc/libX11/libX11/libX11.html

> Focus Window
>
> The XNFocusWindow argument specifies the focus window. The primary
> purpose of the XNFocusWindow is to identify the window that will receive
> the key event when input is composed.
>
> When this XIC value is left unspecified, the input method will use the
> client window as the default focus window.

x.c

@@ -1047,7 +1047,6 @@ ximopen(Display *dpy)
 		xw.ime.xic = XCreateIC(xw.ime.xim, XNInputStyle,
 		                       XIMPreeditNothing | XIMStatusNothing,
 		                       XNClientWindow, xw.win,
-		                       XNFocusWindow, xw.win,
 		                       XNDestroyCallback, &icdestroy,
 		                       NULL);
 	}