Fix potential DoS vector for masternode payments (#2071)
Fix potential DoS vector for masternode payments (#2071)

* Skip only already verified mn payments vote duplicates

* Update mn payment vote stats only if mn payment vote sig is ok

biblepay/biblepay,thelazier/dash,biblepay/biblepay,UdjinM6/dash,dashpay/dash,ionomy/ion,UdjinM6/dash,dashpay/dash,ivansib/sibcoin,dashpay/dash,nmarley/dash,nmarley/dash,ionomy/ion,crowning-/dash,thelazier/dash,thelazier/dash,ivansib/sibcoin,nmarley/dash,nmarley/dash,biblepay/biblepay,UdjinM6/dash,ivansib/sibcoin,nmarley/dash,dashpay/dash,thelazier/dash,crowning-/dash,UdjinM6/dash,biblepay/biblepay,crowning-/dash,ivansib/sibcoin,ionomy/ion,biblepay/biblepay,nmarley/dash,nmarley/dash,dashpay/dash,UdjinM6/dash,ionomy/ion,crowning-/dash,ivansib/sibcoin,crowning-/dash,thelazier/dash,biblepay/biblepay,ionomy/ion,ivansib/sibcoin,ionomy/ion,biblepay/biblepay,biblepay/biblepay,crowning-/dash