Do not restart dns client service as a part of --register-dns processing

Do not restart dns client service as a part of --register-dns processing

As reported and discussed on Trac #775, restarting dns service has
unwanted side effects when there are dependent services. And it
appears unnecessary to restart this service to get DNS registered
on Windows.

Resolve by removing two actions from --register-dns:
'net stop dnscache' and 'net start dnscache' run through the service
or directly.

Trac: #775

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1480542696-7123-1-git-send-email-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13331.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>