Fix for the special case where np=2 and the sendbuf is set to MPI_IN_PLACE.

In that case, sendcount and sendtype are not valid and we need to use
recvcount and recvtype.

This commit fixes trac:943.  Reviewed by Jelena Pjesivac-Grbovic.

This commit was SVN r14022.

The following Trac tickets were found above:
  Ticket 943 --> https://svn.open-mpi.org/trac/ompi/ticket/943

ompi/mca/coll/tuned/coll_tuned_allgather.c

@@ -641,6 +641,8 @@ int ompi_coll_tuned_allgather_intra_two_procs(void *sbuf, int scount,
    tmpsend = (char*)sbuf;
    if (MPI_IN_PLACE == sbuf) {
       tmpsend = (char*)rbuf + rank * rcount * rext;
+      scount = rcount;
+      sdtype = rdtype;
    }
    tmprecv = (char*)rbuf + remote * rcount * rext;