daemon-windows: Ability to handle windows service calls.

The following code does not add any users yet.

The visioned workflow that this piece of code should work with is:
* Create a windows service through a startup script with
a tool like 'sc'
ex:  sc create ovsdb-server binpath=
 "C:\openvswitch\usr\sbin\ovsdb-server.exe -vconsole:off
-vsyslog:off -vfile:info --remote=ptcp:6632:127.0.0.1 --log-file
--service-monitor --service"

* Start the service from the startup script.
ex: sc start ovsdb-server

* Terminate the service during shutdown process.
ex: sc stop ovsdb-server

* Abrupt termination will restart the service.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

lib/daemon.c

@@ -717,3 +717,22 @@ check_already_running(void)
                    pidfile, ovs_strerror(-pid));
     }
 }
+
+
+/* stub functions for non-windows platform. */
+
+void
+service_start(int *argc OVS_UNUSED, char **argv[] OVS_UNUSED)
+{
+}
+
+void
+service_stop(void)
+{
+}
+
+bool
+should_service_stop(void)
+{
+    return false;
+}