LU-9829 lnet: Properly dereference string pointer

LU-9829 lnet: Properly dereference string pointer

A bug highlighted by newer gcc. We really need to be doing
double dereference of the next pointer looking for end of string,
since the pointer is double indirect.

Change-Id: Id80522f43606a843383787d71eec1ddf00af5269
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: https://review.whamcloud.com/28358
Tested-by: Jenkins
Reviewed-by: Patrick Farrell <paf@cray.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>