postgresql: enhanced .conf to build without readline if not installed

database/postgresql/postgresql.conf

@@ -41,6 +41,12 @@ for x in openssl perl python; do
 	fi
 done
 
+for x in readline; do
+	if ! pkginstalled $x; then
+		var_append extraconfopt " " "--without-$x"
+	fi
+done
+
 postgresql_pm() {
 	# Create the data directory
 	mkdir -p $root/$localstatedir/data