client/mysqlbinlog.cc:
  Now my_end() deallocates DBUG by default, but that fails in mysqlbinlog
  because of global destructors that use DBUG.
dbug/dbug.c:
  Add a facility to deallocate the debug stack, to avoid memory leak warnings
  in Valgrind.
include/my_dbug.h:
  Add a facility to deallocate the debug stack, to avoid memory leak warnings
  in Valgrind.
include/my_sys.h:
  Change my_end() to deallocate DBUG memory by default (can be disabled with
  MY_DONT_FREE_DBUG option).
libmysql/libmysql.c:
  Do not deallocate DBUG during cleanup.
mysys/my_init.c:
  Change my_end() to deallocate DBUG memory by default (can be disabled with
  MY_DONT_FREE_DBUG option).
sql/mysqld.cc:
  Add missing my_thread_end() call, seems to occasionally trigger a memory
  leak (not repeatable).