LU-1857 build: fix 'Unbounded source buffer' errors

LU-1857 build: fix 'Unbounded source buffer' errors

Fix 'unbounded source buffer' defects found by Coverity version 6.0.3:
Unbounded source buffer (STRING_SIZE)
Passing string of unknown size to a function that expects
a string of a particular size.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Change-Id: I18e51f04e62241b5c5dad7ae963d8070d6954dd4
Reviewed-on: http://review.whamcloud.com/3904
Tested-by: Hudson
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>