MCA/base: When encounter a duplicate file value don't free the filename.

Stale code.

cmr=v1.7.3:reviewer=rhc
Fix a segfault when a topology file is given to use in place of the one detected by mpirun itself. In that situation, the rmaps framework replaces the opal_hwloc_topology structure - but since that occurs *after* mpirun has set the node->topology field, we lose that definition. So don't set the node->topology field until after the rmaps framework has been opened.

Does not need to go to 1.7 branch as that ordering is different.

-This line, and those below, will be ignored--

M    orte/mca/ess/hnp/ess_hnp_module.c