coll/tuned: make coll_tuned_gather_algorithms MCA settable

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

ompi/mca/coll/tuned/coll_tuned_gather_decision.c

@@ -3,7 +3,7 @@
  * Copyright (c) 2004-2017 The University of Tennessee and The University
  *                         of Tennessee Research Foundation.  All rights
  *                         reserved.
- * Copyright (c) 2015      Research Organization for Information Science
+ * Copyright (c) 2015-2017 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  *
@@ -76,7 +76,7 @@ ompi_coll_tuned_gather_intra_check_forced_init(coll_tuned_force_algorithm_mca_pa
         mca_base_component_var_register(&mca_coll_tuned_component.super.collm_version,
                                         "gather_algorithm",
                                         "Which gather algorithm is used. Can be locked down to choice of: 0 ignore, 1 basic linear, 2 binomial, 3 linear with synchronization.",
-                                        MCA_BASE_VAR_TYPE_INT, new_enum, 0, 0,
+                                        MCA_BASE_VAR_TYPE_INT, new_enum, 0, MCA_BASE_VAR_FLAG_SETTABLE,
                                         OPAL_INFO_LVL_5,
                                         MCA_BASE_VAR_SCOPE_ALL,
                                         &coll_tuned_gather_forced_algorithm);