pgsql: Adjust time qual checking code so that we always check

Log Message:
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Adjust time qual checking code so that we always check TransactionIdIsInProgress
before we check commit/abort status.  Formerly this was done in some paths
but not all, with the result that a transaction might be considered
committed for some purposes before it became committed for others.
Per example found by Jan Wieck.

Tags:
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REL7_4_STABLE

Modified Files:
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    pgsql/src/backend/utils/time:
        tqual.c (r1.70 -> r1.70.2.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/time/tqual.c.diff?r1=1.70&r2=1.70.2.1)