the test_lic_files_chksum_modified_not_mentioned test in patchtest
wasn't picking up on 'License-Update:' tags correctly. Use pyparsing's
AtLineStart class to simplify the regex setup and search.
(From OE-Core rev: dc9126e45e74b915faaf296037e7ece41785bf4a)
Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>