Improve error message from ArcanistXHPASTLinter::LINT_FORMATTED_STRING
Improve error message from ArcanistXHPASTLinter::LINT_FORMATTED_STRING

Summary: Currently the error message from `ArcanistXHPASTLinter::LINT_FORMATTED_STRING` is slightly wrong, mentioning `xsprintf` instead of the actual `sprintf`-style function which was used. This diff changes the error message to be more correct.

Test Plan: Linted a file containing `sprintf('%s')` and saw a reasonable lint message.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12871

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