lib / string_helpers: refactoring the test suite
lib / string_helpers: refactoring the test suite

This patch prepares test suite for a following update.  It introduces
test_string_check_buf() helper which checks the result and dumps an error.

Signed-off-by: Andy Shevchenko <74f0c009df510614346aa771cd21959b78cdb413@linux.intel.com>
Cc: "John W . Linville" <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>
Cc: Johannes Berg <8398eb9892c5ab2ff439ca0b5e4b0706dd9ebef9@sipsolutions.net>
Cc: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>
Cc: Joe Perches <16a9a54ddf4259952e3c118c763138e83693d7fd@perches.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs