hnetcfg: Add stub implementations of INetFwServices and INetFwService.

dlls/hnetcfg/hnetcfg_private.h

diff --git a/dlls/hnetcfg/hnetcfg_private.h b/dlls/hnetcfg/hnetcfg_private.h
index c1f561d..c64bdc2 100644
--- a/dlls/hnetcfg/hnetcfg_private.h
+++ b/dlls/hnetcfg/hnetcfg_private.h
@@ -22,3 +22,4 @@
 HRESULT NetFwAuthorizedApplication_create(IUnknown *, LPVOID *);
 HRESULT NetFwAuthorizedApplications_create(IUnknown *, LPVOID *);
 HRESULT NetFwOpenPorts_create(IUnknown *, LPVOID *);
+HRESULT NetFwServices_create(IUnknown *, LPVOID *);