lndc: use constant time comparison to verify DH proof
lndc: use constant time comparison to verify DH proof

bryanvu/lnd,BitfuryLightning/lnd,BitfuryLightning/lnd,LightningNetwork/lnd,bryanvu/lnd,ddustin/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd,ddustin/lnd,aakselrod/lnd,AndrewSamokhvalov/lnd,LightningNetwork/lnd