use hca distance mapper by default

cmr=v1.7.4:reviewer=ompi-rm1.7

This commit was SVN r29634.

contrib/platform/mellanox/optimized.conf

@@ -59,6 +59,7 @@
 coll_fca_enable = 0
 scoll_fca_enable = 0
 rmaps_base_dist_hca = auto
+rmaps_base_mapping_policy = dist:auto
 coll = ^ml
 hwloc_base_binding_policy = core
 btl = sm,openib,self