Make od print valid addresses for offsets of 2^32 and larger.

Make od print valid addresses for offsets of 2^32 and larger.

(format_address): Use off_t, not long unsigned_int as the
parameter type.
(format_address_none): Likewise.  Mark parameter as unused.
(format_address_std): Likewise.
(format_address_label): Likewise.
(print_ascii): Mark format string parameter as unused.
(write_block): Use off_t, not long unsigned_int as offset type.
(expand_address_fmt): New function.
(main): Use it to expand each address format string template.
Reported by Mark Nudelman, via Andreas Jaeger.