util/lint: Fix linter for old license headers

Somehow I lost a $ on headerlist between when I tested the script
and when I submitted it, turning headerlist into plain text instead
of a variable name.  This makes the test always pass.
- Fix variable bug.
- exclude this script from the check.
- update test for empty HEADER_DIRS variable.

Change-Id: I6080c520bc741e9d689f7c66ee97879afc8ba38c
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/13057
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

0 files changed, 0 insertions, 0 deletions