Item_func_history (is_history()) is a bool function that checks if the
row is the history row by checking row_end->is_max(). The argument to
this function must be row_end system field.
Added the above function to conjunction with SYSTEM_TIME_BEFORE
versioning condition.
MDEV-18957 UPDATE with LIMIT clause is wrong for versioned partitioned tables
UPDATE, DELETE: replace linear search of current/historical records
with vers_setup_conds().
Additional DML cases in view.test
