Add missing include

Refs trac:3800

This commit was SVN r29337.

The following Trac tickets were found above:
  Ticket 3800 --> https://svn.open-mpi.org/trac/ompi/ticket/3800

ompi/mpi/java/c/mpi_Intracomm.c

@@ -25,6 +25,9 @@
 #include "ompi_config.h"
 
 #include <stdlib.h>
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
 #ifdef HAVE_TARGETCONDITIONALS_H
 #include <TargetConditionals.h>
 #endif