(complement, COMPLEMENT_OPTION): New.

(complement, COMPLEMENT_OPTION): New.
(longopts): Add --complement.
(usage): Say not that -b, -c, and -f `print' fields,
but rather that they `select' fields for printing.
Describe the new --complement option.
(mark_range_start): Extracted from set_fields.
(print_kth): Support --complement.
(compare_ranges): New function.
(set_fields): Rewrite the part that populates range_start_ht,
merging it with the part that populates printable_field.
(main): Handle --complement.

From Paolo Bonzini.