Set wxPendingEvents to NULL after deleting it

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20202 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mac/app.cpp

@@ -651,6 +651,7 @@ void wxApp::CleanUp()
         delete wxWinMacControlList ;
     }
     delete wxPendingEvents;
+    wxPendingEvents = NULL;
 
 #if wxUSE_THREADS
     delete wxPendingEventsLocker;

src/mac/carbon/app.cpp

@@ -651,6 +651,7 @@ void wxApp::CleanUp()
         delete wxWinMacControlList ;
     }
     delete wxPendingEvents;
+    wxPendingEvents = NULL;
 
 #if wxUSE_THREADS
     delete wxPendingEventsLocker;