Improved error message for untracked headers
Improved error message for untracked headers

Summary: To simplify the messaging, I omitted platform_headers & friends.

Reviewed By: ttsugriy

fbshipit-source-id: 317fad9

shs96c/buck,Addepar/buck,brettwooldridge/buck,brettwooldridge/buck,SeleniumHQ/buck,JoelMarcey/buck,SeleniumHQ/buck,clonetwin26/buck,zpao/buck,LegNeato/buck,LegNeato/buck,SeleniumHQ/buck,LegNeato/buck,romanoid/buck,shybovycha/buck,brettwooldridge/buck,LegNeato/buck,Addepar/buck,shybovycha/buck,ilya-klyuchnikov/buck,ilya-klyuchnikov/buck,LegNeato/buck,ilya-klyuchnikov/buck,rmaz/buck,shybovycha/buck,kageiit/buck,Addepar/buck,ilya-klyuchnikov/buck,romanoid/buck,zpao/buck,SeleniumHQ/buck,shs96c/buck,kageiit/buck,shybovycha/buck,JoelMarcey/buck,romanoid/buck,zpao/buck,kageiit/buck,kageiit/buck,clonetwin26/buck,shs96c/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,brettwooldridge/buck,brettwooldridge/buck,Addepar/buck,facebook/buck,shs96c/buck,nguyentruongtho/buck,SeleniumHQ/buck,shybovycha/buck,LegNeato/buck,Addepar/buck,clonetwin26/buck,kageiit/buck,shs96c/buck,shs96c/buck,facebook/buck,ilya-klyuchnikov/buck,SeleniumHQ/buck,romanoid/buck,facebook/buck,romanoid/buck,zpao/buck,clonetwin26/buck,k21/buck,JoelMarcey/buck,nguyentruongtho/buck,facebook/buck,rmaz/buck,clonetwin26/buck,shs96c/buck,Addepar/buck,LegNeato/buck,nguyentruongtho/buck,shybovycha/buck,k21/buck,shybovycha/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,romanoid/buck,rmaz/buck,shybovycha/buck,romanoid/buck,Addepar/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,k21/buck,JoelMarcey/buck,romanoid/buck,Addepar/buck,rmaz/buck,JoelMarcey/buck,ilya-klyuchnikov/buck,SeleniumHQ/buck,SeleniumHQ/buck,ilya-klyuchnikov/buck,k21/buck,kageiit/buck,JoelMarcey/buck,brettwooldridge/buck,zpao/buck,ilya-klyuchnikov/buck,SeleniumHQ/buck,brettwooldridge/buck,kageiit/buck,romanoid/buck,clonetwin26/buck,Addepar/buck,ilya-klyuchnikov/buck,LegNeato/buck,brettwooldridge/buck,rmaz/buck,LegNeato/buck,shybovycha/buck,romanoid/buck,clonetwin26/buck,clonetwin26/buck,ilya-klyuchnikov/buck,facebook/buck,brettwooldridge/buck,shs96c/buck,shybovycha/buck,romanoid/buck,shs96c/buck,nguyentruongtho/buck,rmaz/buck,clonetwin26/buck,romanoid/buck,JoelMarcey/buck,zpao/buck,rmaz/buck,shybovycha/buck,Addepar/buck,romanoid/buck,rmaz/buck,clonetwin26/buck,zpao/buck,k21/buck,shs96c/buck,LegNeato/buck,JoelMarcey/buck,shs96c/buck,k21/buck,k21/buck,facebook/buck,shs96c/buck,JoelMarcey/buck,k21/buck,rmaz/buck,SeleniumHQ/buck,k21/buck,JoelMarcey/buck,SeleniumHQ/buck,Addepar/buck,shybovycha/buck,JoelMarcey/buck,nguyentruongtho/buck,k21/buck,Addepar/buck,LegNeato/buck,k21/buck,clonetwin26/buck,clonetwin26/buck,shybovycha/buck,rmaz/buck,brettwooldridge/buck,rmaz/buck,JoelMarcey/buck,clonetwin26/buck,facebook/buck,Addepar/buck,LegNeato/buck,LegNeato/buck,shs96c/buck,rmaz/buck,SeleniumHQ/buck,k21/buck,k21/buck,rmaz/buck,nguyentruongtho/buck,nguyentruongtho/buck,brettwooldridge/buck,SeleniumHQ/buck