don't install bind9-host when setting hostname

also remove an incorrect comment

setup/questions.sh

@@ -207,8 +207,6 @@ if [ "$PUBLIC_IPV6" = "auto" ]; then
 	PUBLIC_IPV6=$(get_publicip_from_web_service 6 || get_default_privateip 6)
 fi
 if [ "$PRIMARY_HOSTNAME" = "auto" ]; then
-	# Use reverse DNS to get this machine's hostname. Install bind9-host early.
-	hide_output apt-get -y install bind9-host
 	PRIMARY_HOSTNAME=$(get_default_hostname)
 elif [ "$PRIMARY_HOSTNAME" = "auto-easy" ]; then
 	# Generate a probably-unique subdomain under our justtesting.email domain.