shcore: Add SubscribeFeatureStateChangeNotification stub.

dlls/api-ms-win-core-featurestaging-l1-1-0/api-ms-win-core-featurestaging-l1-1-0.spec

 @ stub GetFeatureEnabledState
 @ stub RecordFeatureError
 @ stub RecordFeatureUsage
-@ stub SubscribeFeatureStateChangeNotification
+@ stdcall SubscribeFeatureStateChangeNotification(ptr ptr ptr) shcore.SubscribeFeatureStateChangeNotification
 @ stub UnsubscribeFeatureStateChangeNotification

dlls/shcore/main.c

@@ -27,6 +27,7 @@
 #include "winuser.h"
 #include "initguid.h"
 #include "ocidl.h"
+#include "featurestagingapi.h"
 #include "shellscalingapi.h"
 #include "shlwapi.h"
 
@@ -2505,3 +2506,12 @@ BOOL WINAPI IsOS(DWORD feature)
 
     return FALSE;
 }
+
+/*************************************************************************
+ * SubscribeFeatureStateChangeNotification        [SHCORE.@]
+ */
+void WINAPI SubscribeFeatureStateChangeNotification(FEATURE_STATE_CHANGE_SUBSCRIPTION *subscription,
+                                                    FEATURE_STATE_CHANGE_CALLBACK *callback, void *context)
+{
+    FIXME("(%p, %p, %p) stub\n", subscription, callback, context);
+}

dlls/shcore/shcore.spec

@@ -92,7 +92,7 @@
 @ stdcall SetCurrentProcessExplicitAppUserModelID(wstr)
 @ stdcall SetProcessDpiAwareness(long)
 @ stdcall SetProcessReference(ptr)
-# @ stub SubscribeFeatureStateChangeNotification
+@ stdcall SubscribeFeatureStateChangeNotification(ptr ptr ptr)
 @ stub UnregisterScaleChangeEvent
 # @ stub UnsubscribeFeatureStateChangeNotification