dns_server: Cache A record for AAAA query when dualstack select

src/dns_cache.h

@@ -50,6 +50,7 @@ enum CACHE_RECORD_TYPE {
 struct dns_cache_data_head {
 	uint32_t cache_flag;
 	enum CACHE_TYPE cache_type;
+	int is_soa;
 	size_t size;
 };