+ amount field in dpow_vins

dpow_signrawtransaction used signrawtransaction RPC call to daemon
when obtain scriptSig for known notary vin. but signrawtransaction
RPC call in VRSC with activated sapling need to pass amount as required
parameter, otherwise it produced incorrect sig. spent many time
to understand this.

iguana/dpow/dpow_tx.c

@@ -436,6 +436,7 @@ cJSON *dpow_vins(struct iguana_info *coin,struct dpow_block *bp,int8_t bestk,uin
                 item = cJSON_CreateObject();
                 jaddbits256(item,"txid",txid);
                 jaddnum(item,"vout",vout);
+				jaddnum(item, "amount", dstr(dpow_utxosize(coin->symbol)));
                 if ( k == 0 && bp->require0 != 0 )
                 {
                     script[0] = 0x76;