Fixed bugs #12101, #12102: wrong calculation of not_null_tables()
   for some expressions.
   The classes Item_func_between, Item_func_if, Item_func_in are modified.
   Item_func_between/in objects can represent now [NOT]BETWEEN/IN expressions.
   The class Item_func_opt_neg is added to factor out the functionality
   common for the modified classes Item_func_between and Item_func_in.
item_cmpfunc.cc:
  Fixed bugs #12101, #12102: wrong calculation of not_null_tables()
   for some expressions.
   Added Item_func_between::fix_fields(), Item_func_if::fix_fields(),
   Item_func_in::fix_fields(). They correct generic calculation of
   the not_null_tables attribute when it is needed.
   Modified Item_func_between::val_int(), Item_func_in::val_int().
opt_range.cc:
  Fixed bugs #12101, #12102: wrong calculation of not_null_tables()
   for some expressions.
   The function get_mm_tree() is modified. There cannot be NOT before
   BETWEEN/IN anymore. Rather Item_func_between/in objects can represent
   now [NOT]BETWEEN/IN expressions.
sql_yacc.yy:
  Fixed bugs #12101, #12102: wrong calculation of not_null_tables()
   for some expressions.
   Item_func_between/in objects can represent now [NOT]BETWEEN/IN expresions.
join_outer.result:
  Fixed some testcases results (bugs #12101, #12102)
join_outer.test:
  Added testcases for bugs #12101, #12102