Add wide_int version of inchash::hash::add_wide_int

[Jeff Law]

On 10/13/2017 08:05 AM, Richard Sandiford wrote:
> This patch adds an inchash hasher for wide_int-based types.
> It means that hash_tree no longer hashes TREE_INT_CST_EXT_NUNITS,
> but that was redundant with hashing the type.
> 
> Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64-linux-gnu.
> OK to install?
> 
> Richard
> 
> 
> 2017-10-13  Richard Sandiford  <richard.sandiford@linaro.org>
> 
> gcc/
> 	* inchash.h (inchash::hash::add_wide_int): New function.
> 	* lto-streamer-out.c (hash_tree): Use it.
OK.
jeff