BUG #16695: pg_hba_file_rules NULL address and netmask

The following bug has been logged on the website:

Bug reference:      16695
Logged by:          Peter Vandivier
Email address:      petervandivier@gmail.com
PostgreSQL version: 13.0
Operating system:   FreeBSD 11
Description:        

Greetings,

pg_hba_file_rules reports NULL address and netmask values incorrectly on
FreeBSD 11 for tested postgres versions 10-13 (at least). e.g. 

```
sudo su
pkg update -f
pkg install postgresql10-server postgresql10-client
sysrc postgresql_enable=yes
service postgresql initdb
service postgresql start
psql -U postgres -c 'select * from pg_hba_file_rules'
sudo -u postgres cat $(psql -Xtc 'show hba_file') | tail -13
```

All postgres versions appear to report correct values for pg_hba_file_rules
on FreeBSD 12

Cheers,

Peter V