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

samples/toolbar/toolbar.cpp

@@ -725,8 +725,7 @@ void MyFrame::OnToggleAnotherToolbar(wxCommandEvent& WXUNUSED(event))
 {
     if ( m_tbar )
     {
-        delete m_tbar;
-        m_tbar = NULL;
+        wxDELETE(m_tbar);
     }
     else
     {