coll/base: fix MPI_IN_PLACE in ompi_coll_base_reduce_generic()

avoid copying data to itself when MPI_IN_PLACE is used

Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>

ompi/mca/coll/base/coll_base_reduce.c

@@ -99,7 +99,8 @@ int ompi_coll_base_reduce_generic( const void* sendbuf, void* recvbuf, int origi
 
         /* If this is a non-commutative operation we must copy
            sendbuf to the accumbuf, in order to simplfy the loops */
-        if (!ompi_op_is_commute(op)) {
+        
+        if (!ompi_op_is_commute(op) && MPI_IN_PLACE != sendbuf) {
             ompi_datatype_copy_content_same_ddt(datatype, original_count,
                                                 (char*)accumbuf,
                                                 (char*)sendtmpbuf);