mysql_client_binlog_statement

Problem: server may read from unassigned memory performing
"wrong" BINLOG queries.

Fix: never read from unassigned memory.


mysql-test/suite/binlog/r/binlog_base64_flag.result:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - test result.
mysql-test/suite/binlog/t/binlog_base64_flag.test:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - test case.
sql/sql_binlog.cc:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - coded_len should not count trailing '/0';
    - never read from unassigned memory.