Parser changes made by Alexander Barkov <bar@mariadb.com>.
Part of the tests made by Iqbal Hassan <iqbal@hasprime.com>.
Initially marking with ORA_JOIN flag made also by
Iqbal Hassan <iqbal@hasprime.com>.
Main idea is that parser mark fields with (+) with a flag
(ORA_JOIN).
During Prepare the flag bring to the new created items if needed.
Later after preparing (fix_firlds()) WHERE confition the
relations betweel the tables analyzed and tables reordered
so to make JOIN/LEFT JOIN operators in chain equivalent to
the query with oracle outer join operator (+).
Then the flags of (+) removed.
