dns/application: makefile combine: Sort files before combining

Ensures 0_main.db is before other files

roles/dns/application/templates/zones.makefile

@@ -8,4 +8,4 @@ zones:=$(zone_dirs:/=)
 all: $(addprefix ${dest}/,$(addsuffix /${dest_name},${zones}))
 
 ${dest}/%/${dest_name}: %/*.db
-	cat $^ | sed '0,/^  0$$/s//  '"$$(($$(date +%s) / 60))"'/' > "$@";
+	cat $(sort $^) | sed '0,/^  0$$/s//  '"$$(($$(date +%s) / 60))"'/' > "$@";