Removing service-related code in pg_ctl for Cygwin

Hi all,

Beginning a new thread seems more adapted regarding $subject but
that's mentioned here as well:
http://www.postgresql.org/message-id/CAB7nPqQXghm_SdB5iniupz1atzMxk=95gv9A8ocdo83SXCNjeg@mail.gmail.com

It happens based on some investigation from Andrew that cygwin does
not need to use the service-related code, aka register/unregister
options or similar that are proper to WIN32 and rely instead on
cygrunsrv with a SYSV-like init file to manage the service. Based on
my tests with cygwin, I am able to see as well that a server started
within a cygwin session is able to persist even after it is closed,
which is kind of nice and I think that it is a additional reason to
not use the service-related code paths. Hence what about the following
patch, that makes cygwin behave like any *nix OS when using pg_ctl?
This simplifies a bit the code.

Marco, as I think you do some packaging for Postgres in Cygwin, and
others, does that sound acceptable?

Regards,
--
Michael