(size_decoder): Assign to both st->archive_file_size and
st->stat.st_size.
(st->stat.st_size): Assign to st->stat.st_size
(sparse_numbytes_decoder): Removed unused variable
Correctly handle UTF-8 conversions.
(xheader_list_destroy): New function.
(xheader_set_single_keyword,xheader_set_keyword_equal): Added
missing gettext markers
(decode_record): Rewritten using caller-provided handler and
data closure.
(xheader_xhdr_name): Changed the default extended header name
to '%d/PaxHeaders.%p/%f', as POSIX requires.
(xheader_ghdr_name): Removed unused argument.
(xheader_write,xheader_write_global): New function.
(xheader_decode): Modified to honor overrides whatever
the current archive format is.