New common unarchive code.

archival/libunarchive/add_to_list.c

@@ -0,0 +1,15 @@
+#include <stdlib.h>
+#include <string.h>
+#include "unarchive.h"
+#include "libbb.h"
+
+extern const llist_t *add_to_list(const llist_t *old_head, const char *new_item)
+{
+	llist_t *new_head;
+
+	new_head = xmalloc(sizeof(llist_t));
+	new_head->data = new_item;
+	new_head->link = old_head;
+
+	return(new_head);
+}