wireguard: update to 0.0.20180531.
wireguard: update to 0.0.20180531.

NeoChontrix/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,NeoChontrix/void-packages,necrophcodr/void-packages,NeoChontrix/void-packages