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/msw/dialup.cpp

@@ -597,11 +597,7 @@ void wxDialUpManagerMSW::CleanUpThreadData()
         m_hThread = 0;
     }
 
-    if ( m_data )
-    {
-        delete m_data;
-        m_data = NULL;
-    }
+    wxDELETE(m_data);
 }
 
 // ----------------------------------------------------------------------------