add empty _tags file to pacify ocaml
add empty _tags file to pacify ocaml

Summary:
public
In case of compilation error, ocaml would helpfully warn about irrelevant stuff
because infer doesn't look like an ocamlbuild project. Make it look like one.

Reviewed By: jberdine

Differential Revision: D2734392

fb-gh-sync-id: 9761eff

xennygrimmato/infer,ropas/infer,blzq/infer,kstreee/infer,kageiit/infer,jsachs/infer,ropas/infer,kageiit/infer,kageiit/infer,ropas/infer,xennygrimmato/infer,kageiit/infer,jsachs/infer,kageiit/infer,jvillard/infer,blzq/infer,xennygrimmato/infer,xennygrimmato/infer,facebook/infer,kstreee/infer,blzq/infer,jsachs/infer,facebook/infer,xennygrimmato/infer,ropas/infer,facebook/infer,jsachs/infer,jsachs/infer,ryoon/infer,facebook/infer,facebook/infer,ryoon/infer,kstreee/infer,jsachs/infer,ryoon/infer,blzq/infer,blzq/infer,jvillard/infer,xennygrimmato/infer,jvillard/infer,kstreee/infer,jvillard/infer,ryoon/infer,xennygrimmato/infer,jvillard/infer,blzq/infer,kageiit/infer,facebook/infer,jvillard/infer,jvillard/infer,ropas/infer,kstreee/infer,facebook/infer,ryoon/infer,ryoon/infer,kstreee/infer,kageiit/infer,ropas/infer