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/unix/sound.cpp

@@ -570,8 +570,7 @@ bool wxSound::Create(int size, const wxByte* data)
 
         Stop();
 
-        delete ms_backend;
-        ms_backend = NULL;
+        wxDELETE(ms_backend);
 #if wxUSE_LIBSDL && wxUSE_PLUGINS
         delete ms_backendSDL;
 #endif