stdlib functions are used, but no stdlib requirement in metadata.json

[petems]

Error: Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Unknown function: 'validate_hash'. at /etc/puppetlabs/code/environments/production/modules/systemd/manifests/service_limits.pp:13:5 at /etc/puppetlabs/code/environments/production/modules/systemd/foo.pp:1 on node localhost.localdomain

[raphink]

Fixed in c9d2e51