package/libarchive: fix build without zlib

Add upstream patch fixing build without zlib.

Fixes:
http://autobuild.buildroot.net/results/d116d3ace93784722a0914f73dc402746d04b439/



Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>