pg_ctl -w (wait) option on Windows

The attached patch implements the following fixes to pg_ctl on Windows:

- Fix the -w (wait) option to work in Windows service mode, per bug
#3382. This is required on Windows because pg_ctl reports running status
to the service control manager when actually still in recovery/startup,
causing any dependent services to start too early.

- Prevent the -w option being passed to the postmaster.

- Read the postmaster options file when starting as a Windows service.

As a side note, I noticed whilst testing this that the -w option relies
on libpq to provide the username with which to connect to the server to
test the connection. This will fail if that user is not the one that
initialized the cluster, or if the superuser name has been changed. I
hit the former case because I initdb'ed in my dev environment, and then
setup the server to run as a service under a dedicated user account. I
realise this won't affect normal users, and falls neatly into the 'don't
do that then' category, but I thought I'd mention it :-)

Regards, Dave