(read_and):

(read_and):
Do not invoke apply_nonancestor_delayed_set_stat;
DO_SOMETHING is now responsible for that.
Do not invoke apply_delayed_set_stat; our caller is now responsible for that.
(read_header): Use signed char instead of signed_char.
Prevent later references to current_header from
mistakenly treating it as an old GNU header.
(from_header): Quote invalid base-64 strings in diagnostics.
(time_from_header): Do not warn about future timestamps in archive;
check_time now does that.
(tartime): Fix off-by-one error when copying year if OLD_CTIME.
(print_header): Quote unknown file types.
(skip_member): New function, replacing skip_extended_headers and
now skipping the whole member instead of just the extended headers.
All callers changed.  This makes the code handle extended headers
uniformly, and fixes some bugs.