pgsql: When the remote query result has a different number of columns

Log Message:
-----------
When the remote query result has a different number of columns
than the local query specifies (e.g. in the FROM clause),
throw an ERROR (instead of crashing). Fix for bug #2129 reported
by Akio Iwaasa.

Tags:
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REL8_0_STABLE

Modified Files:
--------------
    pgsql/contrib/dblink:
        README.dblink (r1.12 -> r1.12.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/README.dblink.diff?r1=1.12&r2=1.12.4.1)
        dblink.c (r1.38 -> r1.38.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/dblink.c.diff?r1=1.38&r2=1.38.4.1)
        dblink.h (r1.13 -> r1.13.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/dblink.h.diff?r1=1.13&r2=1.13.4.1)
    pgsql/contrib/dblink/doc:
        cursor (r1.3 -> r1.3.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/dblink/doc/cursor.diff?r1=1.3&r2=1.3.4.1)