check-all: don't append '--' to literal commandline

Change-Id: I08b42eabe6f244d6b06bd03924b3612a82b51365
Reviewed-on: http://review.couchbase.org/33003
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>