Added missing "extern "C" {"

src/include/lwip/dns.h

@@ -38,6 +38,10 @@
 
 #if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** DNS timer period */
 #define DNS_TMR_INTERVAL          1000
 
@@ -111,6 +115,10 @@ int            dns_local_removehost(const char *hostname, const ip_addr_t *addr)
 err_t          dns_local_addhost(const char *hostname, const ip_addr_t *addr);
 #endif /* DNS_LOCAL_HOSTLIST && DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* LWIP_DNS */
 
 #endif /* __LWIP_DNS_H__ */