util: Don't allow DecodeBase32(...) of strings with embedded NUL characters
util: Don't allow DecodeBase32(...) of strings with embedded NUL characters

Former-commit-id: e88f4064ab01b640c9fea726bbc1fa9f0fee2be6
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin