Update fluentd to v0.12.18
Update fluentd to v0.12.18

iantalarico/google-fluentd,treasure-data/omnibus-td-agent,GoogleCloudPlatform/google-fluentd,treasure-data/omnibus-td-agent,GoogleCloudPlatform/google-fluentd,treasure-data/omnibus-td-agent,iantalarico/google-fluentd,iantalarico/google-fluentd,GoogleCloudPlatform/google-fluentd