As we no longer use function pointers for read in common archiving code

archive_xread can be replaced with bb_full_read, and archive_copy_file
with bb_copyfd*
bb_copyfd is split into two functions bb_copyfd_size and bb_copyfd_eof,
they share a common backend.

archival/libunarchive/archive_xread_all_eof.c

@@ -24,7 +24,7 @@ extern ssize_t archive_xread_all_eof(archive_handle_t *archive_handle, unsigned
 {
 	ssize_t size;
 
-	size = archive_xread(archive_handle, buf, count);
+	size = bb_full_read(archive_handle->src_fd, buf, count);
 	if ((size != 0) && (size != count)) {
 		bb_perror_msg_and_die("Short read, read %d of %d", size, count);
 	}