rmaps/mindist: better error message

better error message when there is only one socket available

fixed by Elena, reviewed by Miked
cmr=v1.7.5:reviewer=ompi-rm1.7
oshmem: roll back scoll/fca use shmem barrir

have issue, rolling back

fixed by Elena, reviewed by Miked

cmr=v1.7.5:reviewer=ompi-rm1.7