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/generic/renderg.cpp

@@ -183,10 +183,7 @@ wxRendererNative& wxRendererNative::GetGeneric()
 
 void wxRendererGeneric::Cleanup()
 {
-    if (sm_rendererGeneric)
-        delete sm_rendererGeneric;
-
-    sm_rendererGeneric = NULL;
+    wxDELETE(sm_rendererGeneric);
 }
 
 wxRendererGeneric* wxRendererGeneric::sm_rendererGeneric = NULL;