[patch] prevent build warnings from arlex.l and syslex.l

[Alan Modra]

On Tue, Apr 05, 2011 at 08:11:44PM +0200, John Marino wrote:
> +#ifndef YY_NO_UNPUT
>  #define YY_NO_UNPUT
> +#endif

Is there any reason to not use this instead?
#undef YY_NO_UNPUT
#define YY_NO_UNPUT

-- 
Alan Modra
Australia Development Lab, IBM