use "glibc errno" trick not only for ash, but for entire busybox

(add/remove: 1/1 grow/shrink: 37/37 up/down: 139/-228)        Total: -89 bytes

archival/libunarchive/data_skip.c

@@ -3,12 +3,8 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <sys/types.h>
-#include <errno.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include "unarchive.h"
 #include "libbb.h"
+#include "unarchive.h"
 
 void data_skip(archive_handle_t *archive_handle)
 {

archival/libunarchive/seek_by_jump.c

@@ -3,11 +3,6 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <sys/types.h>
-#include <errno.h>
-#include <unistd.h>
-#include <stdlib.h>
-
 #include "libbb.h"
 #include "unarchive.h"