[m-rev.] for review: update header comment in char module

[Peter Wang]

On Wed, 26 Jul 2017 14:41:15 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
> 
> For review by anyone.
> 
> --------------
> 
> Update header comment in char module.
> 
> library/char.m:
>      Delete an out-of-date comment: Mercury characters are Unicode
>      code points, so the set of characters supported and their mapping
>      to integers is not implementation dependent.

That's fine.

Peter