sql/mysql_priv.h:
  initialisation moved to mysqld.cc
sql/mysqld.cc:
  initialisation moved to mysqld.cc
sql/sql_cache.cc:
  support of concurent query cache resizing:
        - resizing made atomic
        - check stack size after each quard mutex lock
sql/sql_cache.h:
  initialisation moved to mysqld.cc
  removed uneed parameter (now it is always under guard mutex protection or called from destruction)