t/Makefile: check helper scripts for non-portable shell commands too
Currently only the "t[0-9][0-9][0-9][0-9]-*.sh" scripts are tested for
shell incompatibilities using the check-non-portable-shell.pl script. This
makes it easy to miss non-POSIX constructs added to one of the t/*lib*.sh
helper scripts, as they aren't automatically detected.
Fix that by adding a THELPERS variable containing all shell scripts that
aren't tests and add these to the "test-lint-shell-syntax" target too.
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>