storing modal returncode correctly for carbon

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63299 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/carbon/msgdlg.cpp

@@ -247,6 +247,8 @@ int wxMessageDialog::ShowModal()
             }
         }
     }
+    
+    SetReturnCode(resultbutton);
 
     return resultbutton;
 }