pgsql: The result of a FULL or RIGHT join can't be assumed to be sorted

Log Message:
-----------
The result of a FULL or RIGHT join can't be assumed to be sorted by the
left input's sorting, because null rows may be inserted at various points.
Per report from Ferenc Lutisch��n.

Modified Files:
--------------
    pgsql/src/backend/optimizer/path:
        joinpath.c (r1.91 -> r1.92)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/joinpath.c.diff?r1=1.91&r2=1.92)
        pathkeys.c (r1.63 -> r1.64)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/pathkeys.c.diff?r1=1.63&r2=1.64)
    pgsql/src/include/optimizer:
        paths.h (r1.77 -> r1.78)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/paths.h.diff?r1=1.77&r2=1.78)