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/widgets/statbmp.cpp

@@ -115,8 +115,7 @@ void StatBmpWidgetsPage::CreateContent()
 
 void StatBmpWidgetsPage::RecreateWidget()
 {
-    delete m_statbmp;
-    m_statbmp = NULL;
+    wxDELETE(m_statbmp);
 
     wxString filepath = m_filepicker->GetPath();
     if ( filepath.empty() )