Re: [HACKERS] pg_hba_file_settings view patch

I wrote:
> I spent awhile hacking on this, and made a lot of things better, but
> I'm still very unhappy about the state of the comments.

I made another pass over this, working on the comments and the docs,
and changing the view name to "pg_hba_file_rules".  I think this version
is committable if people are satisfied with that name.

One loose end is what to do about testing.  I did not much like the
proposed TAP tests.  We could just put "select count(*) > 0 from
pg_hba_file_rules" into the main regression tests, which would provide
some code coverage there, if not very much guarantee that what the view
outputs is sane.