Problem
-------

Binlog encryption feature was designed considering the following OpenSSL
library functions behaviors:
- EVP_BytesToKey function supports EVP_sha512;
- EVP_EncryptUpdate function with padding always encrypts the whole
  source buffer keeping cipher context;
- EVP_DecryptUpdate function with padding always decrypts the whole
  source buffer keeping cipher context and allows decrypting content
  to the same buffer as the source content;

In current WolfSSL library version supported by MySQL 8.0.14 (3.14), the
above mentioned functions behavior is not the same as OpenSSL's.

This patch adapts the Rpl_cipher functions to WolfSSL functions
behavior.