MINOR: pattern: forbid dns resolutions

This patch adds the flags "-n" on the acl parser. the flag "-n" forbif
the DNS resolutions. The maps have always the dns resolutions disabled.
diff --git a/src/acl.c b/src/acl.c
index 7efd89e..8d14c68 100644
--- a/src/acl.c
+++ b/src/acl.c
@@ -428,6 +428,8 @@
 	while (**args == '-') {
 		if ((*args)[1] == 'i')
 			patflags |= PAT_F_IGNORE_CASE;
+		else if ((*args)[1] == 'n')
+			patflags |= PAT_F_NO_DNS;
 		else if ((*args)[1] == 'u') {
 			unique_id = strtol(args[1], &error, 10);
 			if (*error != '\0') {