pg_autovacuum getopt bun in 8.0.0beta5

The getopt specification string for pg_autovacuum in 8.0.0beta5
has:

        while ((c = getopt(argc, argv, "s:S:v:V:a:A:d:U:P:H:L:p:hD:c:C:m:n:l:"))

This has the '-D' demonize option need an argument. So to get it
to run in the background as a daemon, you need to give it a dummy
argument on the command line.

Ken