correct handling of dns fauilure
correct handling of dns fauilure

In case of domain name resolution error result can be negative (see Dns.cpp:46)
knolleary/pubsubclient,tomn46037/pubsubclient,tomn46037/pubsubclient,diegopx/pubsubclient,tectiv3/pubsubclient,tomn46037/pubsubclient,knolleary/pubsubclient,tectiv3/pubsubclient,rubenqba/pubsubclient,diegopx/pubsubclient,mknjc/pubsubclient,mknjc/pubsubclient,mknjc/pubsubclient,rubenqba/pubsubclient,rubenqba/pubsubclient,plugplayco/plugplay-arduino-mqtt,knolleary/pubsubclient,diegopx/pubsubclient,tectiv3/pubsubclient