bug#766: 23.0.60; interesting warning during compilation

[Eli Zaretskii]

> Cc: 766@emacsbugs.donarmstrong.com,
>  bug-gnu-emacs@gnu.org
> From: Peter Dyballa <Peter_Dyballa@Freenet.DE>
> Date: Sat, 23 Aug 2008 16:58:20 +0200
> 
> Could it work to type-cast the variable first into a type wider than  
> 32 bits?

It could, if we could be sure that 64-bit wide integer types are
supported on all platforms.  I don't know if they are; does anyone
know?

(It looks like we use "long long" etc. vary sparingly and only on
platform-specific files, where there's no problem knowing whether it
is supported.)