pgsql: Remove too-smart-for-its-own-good optimization of not overwriting

Log Message:
-----------
Remove too-smart-for-its-own-good optimization of not overwriting the output
files when they haven't changed.  This confuses make because the build fails
to update the file timestamps, and so it keeps on doing the action over again.

Modified Files:
--------------
    pgsql/src/backend/catalog:
        Catalog.pm (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/Catalog.pm?r1=1.1&r2=1.2)
        genbki.pl (r1.1 -> r1.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/genbki.pl?r1=1.1&r2=1.2)