Stop on gen-num-limits failures

[Benjamin Kosnik]

> 	http://gcc.gnu.org/ml/gcc-patches/2001-05/msg01599.html
> 	http://gcc.gnu.org/ml/gcc-patches/2001-04/msg00320.html
> 	http://gcc.gnu.org/ml/gcc-patches/2001-04/msg00325.html

Perhaps Richard could check these in for you?

> Wed May 23 00:13:32 2001  Rainer Orth  <ro@TechFak.Uni-Bielefeld.DE>
> 
> 	* mknumeric_limits: Stop if gen-num-limits dies.

Looks good to me, but I'll let Gaby give his ok and check it in.