Run xhpast in parallel
Run xhpast in parallel

Summary: I wonder if this is not by purpose?

Test Plan: Modified two files, ran `arc lint`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Differential Revision: https://secure.phabricator.com/D2629

eSpark/arcanist,dguo-coursera/arcanist,fivestars/arcanist,PageUpPeopleOrg/arcanist-patches,dguo-coursera/arcanist,memsql/arcanist,codelabs-ch/arcanist,Khan/arcanist,julkiewicz/arcanist,aik099/arcanist,alexmv/arcanist,wharris/arcanist,julkiewicz/arcanist,memsql/arcanist,uber/arcanist,kevinseelbach/arcanist,hach-que/arcanist,phacility/arcanist,wxstars/arcanist,Symplicity/arcanist,PageUpPeopleOrg/arcanist-patches,codelabs-ch/arcanist,calblueprint/arcanist,fivestars/arcanist,codelabs-ch/arcanist,codelabs-ch/arcanist,Khan/arcanist,coursera/arcanist,zhihu/arcanist,fivestars/arcanist,coursera/arcanist,wxstars/arcanist,jra3/arcanist,calblueprint/arcanist,r4nt/arcanist,coursera/arcanist,wharris/arcanist,coursera/arcanist,haskell-infra/arcanist,Symplicity/arcanist,chundongwang/arcanist,PageUpPeopleOrg/arcanist-patches,aik099/arcanist,folsom-labs/arcanist,PageUpPeopleOrg/arcanist-patches,uber/arcanist,alexmv/arcanist,wikimedia/phabricator-arcanist,dguo-coursera/arcanist,wharris/arcanist,julkiewicz/arcanist,zhihu/arcanist,eSpark/arcanist,KieranHayes/arcanist,phacility/arcanist,hach-que/arcanist,julkiewicz/arcanist,Khan/arcanist,calblueprint/arcanist,codelabs-ch/arcanist,chundongwang/arcanist,hach-que/arcanist,folsom-labs/arcanist,aik099/arcanist,kevinseelbach/arcanist,wharris/arcanist,sneakpeeq/arcanist,zhihu/arcanist,haskell-infra/arcanist,calblueprint/arcanist,alexmv/arcanist,phacility/arcanist,chundongwang/arcanist,sneakpeeq/arcanist,haskell-infra/arcanist,memsql/arcanist,folsom-labs/arcanist,jra3/arcanist,dguo-coursera/arcanist,KieranHayes/arcanist,hach-que/arcanist,sneakpeeq/arcanist,zhihu/arcanist,r4nt/arcanist,uber/arcanist,wikimedia/phabricator-arcanist,phacility/arcanist,sneakpeeq/arcanist,uber/arcanist,alexmv/arcanist,phacility/arcanist,r4nt/arcanist,r4nt/arcanist,wikimedia/phabricator-arcanist,eSpark/arcanist,kevinseelbach/arcanist,Symplicity/arcanist,KieranHayes/arcanist,KieranHayes/arcanist,eSpark/arcanist,Khan/arcanist,aik099/arcanist,jra3/arcanist,jra3/arcanist,kevinseelbach/arcanist,wikimedia/phabricator-arcanist,fivestars/arcanist,Symplicity/arcanist,wxstars/arcanist,chundongwang/arcanist,memsql/arcanist,folsom-labs/arcanist,wxstars/arcanist,haskell-infra/arcanist