pgsql: Add a variant expected-output file for the sequence regression

Log Message:
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Add a variant expected-output file for the sequence regression test, to cover
output that is seen when a checkpoint occurs at just the right time during
the test.  Per my report of 2008-08-31.

This could be back-patched but I'm not sure it's worth the trouble.

Added Files:
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    pgsql/src/test/regress/expected:
        sequence_1.out (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/sequence_1.out?rev=1.1&content-type=text/x-cvsweb-markup)