Return actual rtt for nxdomain/nxrrset responses, not 0.
Return actual rtt for nxdomain/nxrrset responses, not 0.

jsha/boulder,jsha/boulder,benileo/boulder,r0ro/boulder,josephyzhou/boulder,lmcro/boulder,deserted/boulder,jcjones/boulder,bmw/boulder,mozmark/boulder,jcjones/boulder,benileo/boulder,ibukanov/boulder,ibukanov/boulder,jmhodges/boulder,tomclegg/boulder,KyleChamberlin/boulder,julienschmidt/boulder,devpaul/boulder,modulexcite/boulder,ZCloud-Firstserver/boulder,jmhodges/boulder,KyleChamberlin/boulder,hlandauf/boulder,patf/boulder,mommel/boulder,lmcro/boulder,r0ro/boulder,devpaul/boulder,tomclegg/boulder,josephyzhou/boulder,mommel/boulder,mozmark/boulder,mozmark/boulder,lmcro/boulder,modulexcite/boulder,josephyzhou/boulder,mehmooda/boulder,jcjones/boulder,bmw/boulder,postfix/boulder,modulexcite/boulder,ZCloud-Firstserver/boulder,jfrazelle/boulder,ZCloud-Firstserver/boulder,bmw/boulder,josephyzhou/boulder,kuba/boulder,mehmooda/boulder,jcjones/boulder,julienschmidt/boulder,postfix/boulder,letsencrypt/boulder,hlandauf/boulder,deserted/boulder,benileo/boulder,jfrazelle/boulder,sophie-h/boulder,benileo/boulder,patf/boulder,kuba/boulder,mommel/boulder,deserted/boulder,mehmooda/boulder,lmcro/boulder,deserted/boulder,kuba/boulder,kuba/boulder,lucasallan/boulder,hlandauf/boulder,devpaul/boulder,ibukanov/boulder,ZCloud-Firstserver/boulder,sophie-h/boulder,lucasallan/boulder,letsencrypt/boulder,mozmark/boulder,jfrazelle/boulder,julienschmidt/boulder,postfix/boulder,patf/boulder,jfrazelle/boulder,mommel/boulder,tomclegg/boulder,KyleChamberlin/boulder,patf/boulder,postfix/boulder,hlandauf/boulder,r0ro/boulder,jmhodges/boulder,sophie-h/boulder,modulexcite/boulder,lucasallan/boulder,mehmooda/boulder,tomclegg/boulder,KyleChamberlin/boulder,letsencrypt/boulder,julienschmidt/boulder,r0ro/boulder,jsha/boulder,jmhodges/boulder,devpaul/boulder