Fix removing event handler filters in wxEvtHandler.

Removal from the simply linked list of event filters wasn't done correctly as
the pointer to the previous node was never updated.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71538 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/event.cpp

@@ -1162,6 +1162,8 @@ wxEventFilter* wxEvtHandler::ms_filterList = NULL;
             // Skip the assert below.
             return;
         }
+
+        prev = f;
     }
 
     wxFAIL_MSG( "Filter not found" );