tools: add zip utility

One image requires a zip compressed image, so add the zip util found in
the packages feed, and extend it with some useful debian patches.

Signed-off-by: Mathias Kresin <dev@kresin.me>

tools/zip/patches/006-stack-markings-to-avoid-executable-stack.patch

@@ -0,0 +1,21 @@
+From: Kees Cook <kees@debian.org>
+Subject: put stack markings in i386 assembly to avoid executable stack
+Bug-Debian: http://bugs.debian.org/528280
+X-Debian-version: 3.0-2
+
+--- a/crc_i386.S
++++ b/crc_i386.S
+@@ -302,3 +302,5 @@ _crc32:                         /* ulg c
+ #endif /* i386 || _i386 || _I386 || __i386 */
+ 
+ #endif /* !USE_ZLIB && !CRC_TABLE_ONLY */
++.section .note.GNU-stack, "", @progbits
++.previous
+--- a/match.S
++++ b/match.S
+@@ -405,3 +405,5 @@ L__return:
+ #endif /* i386 || _I386 || _i386 || __i386  */
+ 
+ #endif /* !USE_ZLIB */
++.section .note.GNU-stack, "", @progbits
++.previous