pgsql: Fix mishandling of whole-row Vars referencing a view or

Log Message:
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Fix mishandling of whole-row Vars referencing a view or sub-select.
If such a Var appeared within a nested sub-select, we failed to translate it
correctly during pullup of the view, because the recursive call to
replace_rte_variables_mutator was looking for the wrong sublevels_up value.
Bug was introduced during the addition of the PlaceHolderVar mechanism.
Per bug #5514 from Marcos Castedo.

Tags:
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REL8_4_STABLE

Modified Files:
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    pgsql/src/backend/optimizer/prep:
        prepjointree.c (r1.66.2.1 -> r1.66.2.2)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/prep/prepjointree.c?r1=1.66.2.1&r2=1.66.2.2)
    pgsql/src/test/regress/expected:
        subselect.out (r1.22 -> r1.22.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/subselect.out?r1=1.22&r2=1.22.2.1)
    pgsql/src/test/regress/sql:
        subselect.sql (r1.14 -> r1.14.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/subselect.sql?r1=1.14&r2=1.14.2.1)