uninitialized value fixed


sql/item_cmpfunc.cc:
  fixed uninitialized used_tables_cache
  othyer caches moved on proper place
sql/item_subselect.cc:
  fixed reported table bit
sql/mysql_priv.h:
  after merge chenges.
sql/sql_parse.cc:
  used same new operator for all allocation in subroutine
sql/sql_union.cc:
  fake st_select_lex should have item list for ref_array allocation
sql/sql_yacc.yy:
  after merge changing