LU-4727 hsm: use IOC_MDC_GETFILEINFO in restore

LU-4727 hsm: use IOC_MDC_GETFILEINFO in restore

Use IOC_MDC_GETFILEINFO rather than fstatat() to get the original file
attributes during restore. Add test_12p to sanity-hsm to check that
triggering an implicit restore from the copytool's own mount point
does not wedge the copytool.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I1b1eeb703c60907a2759fdb6d8fb8728a13f8918
Reviewed-on: http://review.whamcloud.com/13750
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>