Use wxDELETE() and wxDELETEA() when possible.

Use wxDELETE[A]() functions which automatically NULL out their arguments after
deleting them instead of doing it manually.

Closes #9685.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64656 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/dlgcmn.cpp

@@ -680,8 +680,7 @@ bool wxStandardDialogLayoutAdapter::DoLayoutAdaptation(wxDialog* dialog)
                     stdButtonSizer->Realize();
                 else
                 {
-                    delete buttonSizer;
-                    buttonSizer = NULL;
+                    wxDELETE(buttonSizer);
                 }
             }