bug#9496: 24.0.50; Segfault on TAB-only composition

[Eli Zaretskii]

> Date: Fri, 03 Feb 2012 11:28:29 -0800
> From: Paul Eggert <eggert@cs.ucla.edu>
> 
> -static int
> +static EMACS_INT
>  char_width (int c, struct Lisp_Char_Table *dp)
>  {
> -  int width = CHAR_WIDTH (c);
> +  EMACS_INT width = CHAR_WIDTH (c);

Oh, come on!  CHAR_WIDTH returns the character's width
_on_the_screen_.  So how in the world could it _ever_ overflow a
32-bit integer??