fixed windows build error

src/net.cpp

@@ -1868,15 +1868,15 @@ bool BindListenPort(const CService &addrBind, string& strError)
     // some systems don't have IPV6_V6ONLY but are always v6only; others do have the option
     // and enable it by default or not. Try to enable it, if possible.
     if (addrBind.IsIPv6()) {
-#ifdef IPV6_V6ONLY
-        setsockopt(hListenSocket, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&nOne, sizeof(int));
-#endif
 #ifdef WIN32
         int nProtLevel = 10 /* PROTECTION_LEVEL_UNRESTRICTED */;
         int nParameterId = 23 /* IPV6_PROTECTION_LEVEl */;
         // this call is allowed to fail
         setsockopt(hListenSocket, IPPROTO_IPV6, nParameterId, (const char*)&nProtLevel, sizeof(int));
+#elif IPV6_V6ONLY
+	setsockopt(hListenSocket, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&nOne, sizeof(int));
 #endif
+ 
     }
 #endif