pgsql: Convert tabs to spaces in SGML.

Log Message:
-----------
Convert tabs to spaces in SGML.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        backup.sgml (r2.131 -> r2.132)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/backup.sgml?r1=2.131&r2=2.132)
        config.sgml (r1.239 -> r1.240)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.239&r2=1.240)
        func.sgml (r1.494 -> r1.495)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.494&r2=1.495)