remove unused struct

since f24b46c2
    loplugin:unusedfields in vcl

Change-Id: Idef892664a7c53c15e27685fdb7faa36d8b81f30
Reviewed-on: https://gerrit.libreoffice.org/40327Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jochen Nitschke <j.nitschke+logerrit@ok.de>

vcl/source/app/svapp.cxx

@@ -154,12 +154,6 @@ extern "C" {
     typedef UnoWrapperBase* (SAL_CALL *FN_TkCreateUnoWrapper)();
 }
 
-struct ImplEventHook
-{
-    void*                   mpUserData;
-    VCLEventHookProc        mpProc;
-};
-
 struct ImplPostEventData
 {
     VclEventId      mnEvent;