[10/12] Add helper class for valued-based empty and deleted slots

[Jeff Law]

On 06/23/2015 08:55 AM, Richard Sandiford wrote:
> part_traits in cfgexpand.c needs to use the value rather than the key to
> represent empty and deleted slots.  What it's doing is pretty generic,
> so this patch adds a helper class to hash-map-traits.h.
>
>
> gcc/
> 	* hash-map-traits.h (unbounded_hashmap_traits): New class.
> 	(unbounded_int_hashmap_traits): Likewise.
> 	* cfgexpand.c (part_traits): Use unbounded_int_hashmap_traits.
OK.
jeff