LU-4569 hsm: Specify import source by FID.

LU-4569 hsm: Specify import source by FID.

Make the posix CT also accept a FID as import source parameter (from
which the path can be rebuilt) to allow easy "undeletion" of archived
files:

lhsmtool_posix --import <fid> /mnt/lustre/undelete ...

This patch also fixes a typo and replaces a bulky path construction by
a single asprintf() statement.

Lustre-change: http://review.whamcloud.com/9075
Lustre-commit a847e69c3b3853f547f99fcbb9c77259c4f3aa05

Change-Id: Id77841fe7c118872dba9654e88980585485e0ee4
Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-on: http://review.whamcloud.com/10132
Tested-by: Jenkins
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>