Stop mpidummy contamination

Created by: chuckatkins

@pnorbert @williamfgc This should let us kill off mpidummy.h from public interface and restrict it to internal use only.

source/adios2/core/Engine.h

@@ -23,8 +23,8 @@
 
 #include "adios2/ADIOS.h"
 #include "adios2/ADIOSConfig.h"
-#include "adios2/ADIOSTypes.h"
 #include "adios2/ADIOSMPICommOnly.h"
+#include "adios2/ADIOSTypes.h"
 #include "adios2/core/Capsule.h"
 #include "adios2/core/Method.h"
 #include "adios2/core/Transform.h"