rename archival/libunarchive -> archival/libarchive; move bz/ into it

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/unzip.c b/archival/unzip.c
index 204e349..5d62c08 100644
--- a/archival/unzip.c
+++ b/archival/unzip.c
@@ -20,7 +20,7 @@
  */
 
 #include "libbb.h"
-#include "unarchive.h"
+#include "archive.h"
 
 enum {
 #if BB_BIG_ENDIAN