fix harmless warnings about uninitialized (not really) variables in MSVC release build

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61384 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/logg.cpp

@@ -373,7 +373,7 @@ void wxLogGui::DoLogRecord(wxLogLevel level,
                 wxFrame *pFrame = NULL;
 
                 // check if the frame was passed to us explicitly
-                wxUIntPtr ptr;
+                wxUIntPtr ptr = NULL;
                 if ( info.GetNumValue(wxLOG_KEY_FRAME, &ptr) )
                 {
                     pFrame = static_cast<wxFrame *>(wxUIntToPtr(ptr));