pgsql: In a nestloop inner indexscan, it's OK to use pushed-down

Log Message:
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In a nestloop inner indexscan, it's OK to use pushed-down baserestrictinfo
clauses even if it's an outer join.  This is a corner case since such
clauses could only arise from weird OUTER JOIN ON conditions, but worth
fixing.  Per example from Ron at cheapcomplexdevices.com.

Tags:
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REL8_1_STABLE

Modified Files:
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    pgsql/src/backend/optimizer/path:
        indxpath.c (r1.191.2.3 -> r1.191.2.4)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/indxpath.c.diff?r1=1.191.2.3&r2=1.191.2.4)