pgsql: Change warning-silencing code not to cast the pointer type,

[mha(at)postgresql(dot)org (Magnus Hagander)]

Log Message:
-----------
Change warning-silencing code not to cast the pointer type, instead
casting the value of the variable later.

Per comments from Tom.

Modified Files:
--------------
    pgsql/src/test/regress:
        pg_regress.c (r1.58 -> r1.59)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.c?r1=1.58&r2=1.59)