CBase58Data::SetString: cleanse the full vector
CBase58Data::SetString: cleanse the full vector

SetString seems to be passing the length of the wrong variable to
memory_cleanse, resulting in the last byte of the temporary buffer not being
securely erased.

dagurval/bitcoinxt,bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt