LU-4984 llite: check for integer overflow in hsm user request

LU-4984 llite: check for integer overflow in hsm user request

Check to make sure total size of request does not overflow when
calculated.  Return -1 from hur_len() if it does overflow.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I6a3ca50c53ff38dab4165f20dac6fa00eb888df2
Reviewed-on: http://review.whamcloud.com/10615
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>