Fix chainstate serialized_size computation
Fix chainstate serialized_size computation

backports bitcoin@298e040bca0aad62b616a1d3e66e1e44d2b9bd3a
PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,PIVX-Project/PIVX,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet,Darknet-Crypto/Darknet