Problem: copying issuer's (or subject's) name tags into an internal
buffer from incoming stream we didn't check the buffer overflow. 
That may lead to memory overrun, crash etc.

Fix: ensure we don't overrun the buffer.

Note: there's no simple test case (exploit needed).


extra/yassl/taocrypt/include/asn.hpp:
  Fix for bug#50227: Pre-auth buffer-overflow in mySQL through yaSSL
    - CertDecoder::AddTag() introduced.
extra/yassl/taocrypt/src/asn.cpp:
  Fix for bug#50227: Pre-auth buffer-overflow in mySQL through yaSSL
    - copying data from incoming stream to the issuer_ or subject_
  buffers ensure we don't overrun them.
    - code cleanup.