Use scope guard to ensure that free() is called in wxTLW code

No real changes, just make the code safer by ensuring that free() is
always called instead of doing it manually.

src/msw/toplevel.cpp

@@ -38,6 +38,7 @@
 #endif //WX_PRECOMP
 
 #include "wx/dynlib.h"
+#include "wx/scopeguard.h"
 #include "wx/tooltip.h"
 
 #include "wx/msw/private.h"
@@ -438,6 +439,8 @@ bool wxTopLevelWindowMSW::Create(wxWindow *parent,
         // don't use DS_SETFONT we don't need the fourth WORD for the font)
         static const int dlgsize = sizeof(DLGTEMPLATE) + (sizeof(WORD) * 3);
         DLGTEMPLATE *dlgTemplate = (DLGTEMPLATE *)malloc(dlgsize);
+        wxON_BLOCK_EXIT1(free, dlgTemplate);
+
         memset(dlgTemplate, 0, dlgsize);
 
         // these values are arbitrary, they won't be used normally anyhow
@@ -470,7 +473,6 @@ bool wxTopLevelWindowMSW::Create(wxWindow *parent,
             dlgTemplate->style |= DS_MODALFRAME;
 
         ret = CreateDialog(dlgTemplate, title, pos, sizeReal);
-        free(dlgTemplate);
     }
     else // !dialog
     {