There was memory leak when running some tests on PB2.
The reason of the failure is an early return from change_master()
that was supposed to deallocate a dyn-array.

Actually the same bug58915 was fixed in trunk with relocating the dyn-array
destruction into THD::cleanup_after_query() which can't be bypassed.
The current patch backports magne.mahre@oracle.com-20110203101306-q8auashb3d7icxho
and adds two optimizations: were done: the static buffer for the dyn-array to base on,
and the array initialization is called precisely when it's necessary rather than
per each CHANGE-MASTER as before.


mysql-test/suite/rpl/t/rpl_empty_master_host.test:
  the test is binlog-format insensitive so it will be run with MIXED mode only.
mysql-test/suite/rpl/t/rpl_server_id_ignore.test:
  the test is binlog-format insensitive so it will be run with MIXED mode only.
sql/sql_class.cc:
  relocating the dyn-array
  destruction into THD::cleanup_after_query().
sql/sql_lex.cc:
  LEX.mi zero initialization is done in LEX().
sql/sql_lex.h:
  Optimization for repl_ignore_server_ids to base on a static buffer
  which size is chosen to fit to most common use cases.
sql/sql_repl.cc:
  dyn-array destruction is relocated to THD::cleanup_after_query().
sql/sql_yacc.yy:
  Refining logics of Lex->mi.repl_ignore_server_ids initialization.
  The array is initialized once a corresponding option in CHANGE MASTER token sequence
  is found.