Cleanup during reviews of new pushed code


BUILD/compile-pentium-debug-max:
  Use --debug=full as default
BUILD/compile-pentium-debug:
  Use --debug=full as default
mysys/my_alloc.c:
  More debugging
sql/item_func.cc:
  Cleanup new code
  Don't call insert_id() for last_insert_id(value) to avoid side effects
sql/item_subselect.cc:
  Fixed DBUG output
sql/sp_head.cc:
  Simple cleanup
sql/sql_lex.cc:
  Moved usage of arguments first in lex_start to make their usage clearer
  Remove sl->expr_list.deleete_elements() becasue:
  - It didn't do anything (delete_elements on a list of list is a no-op operation)
  - The deleted for loop used SELECT_LEX elements that was allocated in mysql_new_select() in sp-head, but freed
  when sphead->mem_root was freed. (delete sphead doesn't remove used SELECT_LEX elements from the global all_selects_list)
sql/sql_parse.cc:
  More DBUG entries