toplev.c (read_integral_parameter): Constify.

toplev.c (read_integral_parameter): Constify.

        * toplev.c (read_integral_parameter): Constify.  Better control of
        error messages.
        (main): Use read_integral_parameter to set optimize, id_clash_len,
        larger_than_size, and the debugging level.
        * toplev.h (read_integral_parameter): Update prototype.

From-SVN: r25856