Remove "async lint" from arc lint
Summary: Ref T12996. This was a very old FB-specific feature that caused some kind of server-side lint thing to run. You can/should do this now with Harbormaster instead. Nothing else ever used it and it has no role in the upstream.
Test Plan: Grepped for asynclint, created this revision.
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T12996
Differential Revision: https://secure.phabricator.com/D18641