[WINSTA] Add some missing stubs (#2307)

Add stubs for WinStationCanLogonProceed() and _WinStationOpenSessionDirectory() functions to make winlogon from Windows Server 2003 happy.

CORE-15392 CORE-16458

dll/win32/winsta/logon.c

···
 {
     UNIMPLEMENTED;
 }
+
+VOID
+WINSTAAPI WinStationCanLogonProceed(PVOID A,
+                                    PVOID B,
+                                    PVOID C)
+{
+    UNIMPLEMENTED;
+}
+
+VOID
+WINSTAAPI _WinStationOpenSessionDirectory(PVOID A,
+                                          PVOID B)
+{
+    UNIMPLEMENTED;
+}

dll/win32/winsta/winsta.spec

···
 @ stdcall WinStationActivateLicense(ptr ptr ptr ptr)
 @ stdcall WinStationAutoReconnect(ptr)
 @ stdcall WinStationBroadcastSystemMessage(ptr ptr ptr ptr ptr ptr ptr ptr ptr ptr)
+@ stdcall WinStationCanLogonProceed(ptr ptr ptr)
 @ stdcall WinStationCheckAccess(ptr ptr ptr)
 @ stdcall WinStationCheckLoopBack(ptr ptr ptr ptr)
 @ stdcall WinStationCloseServer(ptr ptr ptr ptr)
···
 @ stdcall _WinStationNotifyLogoff()
 @ stdcall _WinStationNotifyLogon(ptr ptr ptr ptr ptr ptr ptr ptr)
 @ stdcall _WinStationNotifyNewSession(ptr ptr)
+@ stdcall _WinStationOpenSessionDirectory(ptr ptr)
 @ stdcall _WinStationReInitializeSecurity(ptr)
 @ stdcall _WinStationReadRegistry(ptr)
 @ stdcall _WinStationSessionInitialized()