patch to avoid xmalloc uses for hash tables

[Andrew Cagney]

> This is OK.  It would be nice if the libiberty update and this
>> patch could be synchronised.  We're still using the old one in src/.
> 
> 
> Intentional but temporary.  The libiberty in gcc is broken.  As soon
> as it's fixed I'll sync again.

Thanks for [er not?] doing this :-)

Andrew