pgsql: Close all cursors created during a failed subtransaction.

Log Message:
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Close all cursors created during a failed subtransaction.  This is needed
to avoid problems when a cursor depends on objects created or changed in
the same subtransaction.  We'd like to do better someday, but this seems
the only workable answer for 8.0.1.

Tags:
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REL8_0_STABLE

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        rollback_to.sgml (r1.5 -> r1.5.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/rollback_to.sgml.diff?r1=1.5&r2=1.5.4.1)
    pgsql/src/backend/utils/mmgr:
        portalmem.c (r1.76 -> r1.76.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/mmgr/portalmem.c.diff?r1=1.76&r2=1.76.4.1)