EX-5260 pumount: test pumount with MDT0000 unmounted

EX-5260 pumount: test pumount with MDT0000 unmounted

Add tests (40a-40c, 41a) to verify that pumount can unmount a client
mount point with MDT0000 and OST0000 unmounted. Add a test (34a) that
pumount does not kill processes who are minding their own business on
other Lustre client mount points.

Test-Parameters: testlist=sanity-pumount,sanity-pumount,sanity-pumount clientextra_install_params="--packages pumount"
Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I02b603d1c6de9f10605d3e315d5149de72698e73
Reviewed-on: https://review.whamcloud.com/47389
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>