Previous output value must be set at time of transaction creation

[jrick]

One of the requirements for decred/dcrd#950 is for the wallet to set the previous output value in the transaction input that references the output. Currently this field is set by miners, but the new signature hash algorithm will use the input value for the signature calculation.

There are several places where transactions can be created by the wallet, so a full audit should be performed to ensure all are updated.

[jrick]

I believe this is fixed everywhere now, since wire.NewTxIn was modified to require the input amount.