of sparse_map_size. We assume that whatever number it contains
describes adequately the current size of sparse_map. The only
number we need to reset is sparse_map_avail.
(struct tar_sparse_optab.fixup_header): New member
(tar_sparse_member_p): New function.
(tar_sparse_init): Return true if decode_header is not provided
(tar_sparse_fixup_header)
(sparse_member_p,sparse_fixup_header)
(sparse_skip_file)
(oldgnu_sparse_member_p,oldgnu_fixup_header,star_sparse_member_p)
(star_fixup_header, pax_sparse_member_p): New function
(pax_decode_header): Remove