Remove spurious addToIndex in CxxBinaryDescription.createBuildRule
Remove spurious addToIndex in CxxBinaryDescription.createBuildRule

Summary:
This should be handled by callers, especially since callers delegate to this
method from Description.createBuildRule implementations, whose return values
are added to the index by BuildRuleResolver automatically.

Test Plan: CI

fbshipit-source-id: b806958

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