Re: fix psql \conninfo & \connect when using hostaddr

>> I'm working on improving the patch.
>
> Cool.

Here is the updated v2

  - libpq internal function getHostaddr get a length,
    and I added an assert about it.
  - added a few braces on if/if/else/if/else/else
  - added an UNKNOWN_HOST macro to hide "???"
  - moved host_addr[] declaration earlier to avoid some braces
  - I have not refactored psql connection message,
    but finally agree with Pavel & you have a point.

-- 
Fabien.