Add in missing header file

This commit was SVN r24662.

opal/datatype/opal_datatype_cuda.c

@@ -15,6 +15,7 @@
 
 #include "opal/align.h"
 #include "opal/mca/base/mca_base_param.h"
+#include "opal/util/output.h"
 #include "orte/util/show_help.h"
 #include "opal/datatype/opal_convertor.h"
 #include "opal/datatype/opal_datatype_cuda.h"