always re-initialize vmhole *before* mca_base_component_var_register()
otherwise the vmhole gets NULL'ified if orte is initialized a second time.
that typically occurs when Open MPI is configure'd with --disable-dlopen
and the app does MPI_T_init_thread(); MPI_T_finalize(); MPI_T_init_thread();
Signed-off-by: Gilles Gouaillardet <gilles@rist.or.jp>