Post-merge fixes for nested joins.
  The join_tab_cmp function in sql_select has been changed.
join_nested.result:
  Post-merge fixes for nested joins. 
  The join_tab_cmp function in sql_select has been changed
sql_select.cc:
  Post-merge fixes for nested joins.
  Avoided re-execution of eliminate_not_funcs and simplify_joins
  in optimize_cond.
  Changed the join_tab_cmp function to take into account
  the dependent relation.
sql_lex.cc, sql_lex.h:
  Added the first_cond_optimization flag to st_select_lex to avoid
  re-execution of some optimizations in optimize_cond.
sql_base.cc:
  Post-merge fixes for nested joins. 
  Fixed problems with a proper column list substituted for '*' in
  queries with natural joins.