Added stub code for MPI_Intercomm_merge

Makefile

@@ -19,6 +19,7 @@ SRCS_C		= mpi.c \
 		  handles.c \
                   comm.c \
 		  error.c \
+                  ic_merge.c \
                   group.c \
                   time.c \
                   pack.c \

ic_merge.c

@@ -0,0 +1,15 @@
+
+#include "mpiP.h"
+
+/*
+ * MPI_Intercomm_merge - Creates an intracommunicator from an intercommunicator
+ * This is just a stub for now to support mpi function calls even in Serial
+ * applications. In the case of a serial program, this function is a no-op and 
+ * only ever returns MPI_SUCCESS
+ */
+
+int MPI_Intercomm_merge( MPI_Comm intercomm, int high, MPI_Comm *newintracomm )
+{
+  newintracomm = (MPI_Comm *)intercomm;
+  return(MPI_SUCCESS);
+}

mpi.h

@@ -253,7 +253,8 @@ typedef int MPI_Info;         /* handle */
 extern int MPI_Intercomm_create(MPI_Comm local_comm, int local_leader,
                           MPI_Comm peer_comm, int remote_leader,
                           int tag, MPI_Comm *newintercomm); 
-
+extern int MPI_Intercomm_merge(MPI_Comm intercomm, int high,
+			       MPI_Comm *newintercomm);
 extern int MPI_Cart_create(MPI_Comm comm_old, int ndims, int *dims,
                         int *periods, int reorder, MPI_Comm *comm_cart);
 extern int MPI_Cart_get(MPI_Comm comm, int maxdims, int *dims,