fix error reporting for enum_net_interfaces

src/enum_net.cpp

@@ -426,10 +426,9 @@ namespace libtorrent
 	{
 		TORRENT_UNUSED(ios); // this may be unused depending on configuration
 		std::vector<ip_interface> ret;
+		ec.clear();
 #if defined TORRENT_BUILD_SIMULATOR
 
-		TORRENT_UNUSED(ec);
-
 		std::vector<address> ips = ios.get_ips();
 
 		for (int i = 0; i < int(ips.size()); ++i)