Print out the locations of libphutil and arcanist when arc is run with --trace
Print out the locations of libphutil and arcanist when arc is run with --trace

Summary: We currently print //additional// libraries, but not the core libraries, which makes diagnosing include problems more difficult than necessary.

Test Plan: ran `arc derp --trace`, got libphutil/arcanist locations

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D2929

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