pgsql: Previous fix for "x FULL JOIN y ON true" failed to handle the

Log Message:
-----------
Previous fix for "x FULL JOIN y ON true" failed to handle the case
where there was also a WHERE-clause restriction that applied to the
join.  The check on restrictlist == NIL is really unnecessary anyway,
because select_mergejoin_clauses already checked for and complained
about any unmergejoinable join clauses.  So just take it out.

Tags:
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REL8_0_STABLE

Modified Files:
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    pgsql/src/backend/optimizer/path:
        joinpath.c (r1.91.4.1 -> r1.91.4.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/joinpath.c.diff?r1=1.91.4.1&r2=1.91.4.2)