Print version_comment after server version in:
mysql.cc:  Welcome message and 'status' command output
log.cc: Top of log files


client/mysql.cc:
  Add server_version_string() function to return a buffer with the server version and version_comment combined.
  Use server_version_string() instead of mysql_get_server_info() for Welcome! message and 'status' command
sql/log.cc:
  MYSQL_LOG::open():
  - print MYSQL_COMPILATION_COMMENT after the server_version at the top of log files