Minor cleanup required when configuring with an external libevent. Thanks to Orion Poplawski for the patch!

cmr=v1.7.4:reviewer=ompi-gk1.7

This commit was SVN r30543.

opal/class/opal_hotel.h

@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2012-2013 Cisco Systems, Inc. All rights reserved.
  * Copyright (c) 2012      Los Alamos National Security, LLC. All rights reserved
+ * Copyright (c) 2014      Intel, Inc. All rights reserved
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -55,6 +56,7 @@
 #include "opal/prefetch.h"
 #include "opal/class/opal_object.h"
 #include "opal/mca/event/event.h"
+#include "opal/prefetch.h"
 
 BEGIN_C_DECLS