rpm2cpio: handle unseekable input correctly

function                                             old     new   delta
data_skip                                             14      20      +6
seek_by_jump                                          67      72      +5
data_align                                            81      84      +3
seek_by_read                                          20      19      -1
skip_header                                           99      94      -5
rpm2cpio_main                                        183     177      -6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/3 up/down: 14/-12)              Total: 2 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/libunarchive/seek_by_jump.c b/archival/libunarchive/seek_by_jump.c
index 0a259c9..7181cb3 100644
--- a/archival/libunarchive/seek_by_jump.c
+++ b/archival/libunarchive/seek_by_jump.c
@@ -6,13 +6,13 @@
 #include "libbb.h"
 #include "unarchive.h"
 
-void FAST_FUNC seek_by_jump(const archive_handle_t *archive_handle, unsigned amount)
+void FAST_FUNC seek_by_jump(int fd, off_t amount)
 {
 	if (amount
-	 && lseek(archive_handle->src_fd, (off_t) amount, SEEK_CUR) == (off_t) -1
+	 && lseek(fd, amount, SEEK_CUR) == (off_t) -1
 	) {
 		if (errno == ESPIPE)
-			seek_by_read(archive_handle, amount);
+			seek_by_read(fd, amount);
 		else
 			bb_perror_msg_and_die("seek failure");
 	}