Fixed bug #49895: Incorrect configuration detection in lwip/dns.h

Signed-off-by: goldsimon <goldsimon@gmx.de>
diff --git a/src/include/lwip/dns.h b/src/include/lwip/dns.h
index 3753a53..2d147af 100644
--- a/src/include/lwip/dns.h
+++ b/src/include/lwip/dns.h
@@ -61,7 +61,7 @@
 #ifndef LWIP_DNS_ADDRTYPE_DEFAULT
 #define LWIP_DNS_ADDRTYPE_DEFAULT   LWIP_DNS_ADDRTYPE_IPV4_IPV6
 #endif
-#elif defined(LWIP_IPV4)
+#elif LWIP_IPV4
 #define LWIP_DNS_ADDRTYPE_DEFAULT   LWIP_DNS_ADDRTYPE_IPV4
 #else
 #define LWIP_DNS_ADDRTYPE_DEFAULT   LWIP_DNS_ADDRTYPE_IPV6