package/upx: needs zlib

Fixes build issues like, observed on a stripped-down build system:
    compress.cpp:32:18: fatal error: zlib.h: No such file or directory
     #include <zlib.h>
                  ^
    compilation terminated.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/upx/upx.mk

@@ -10,7 +10,7 @@ UPX_SOURCE = upx-$(UPX_VERSION)-src.tar.bz2
 UPX_LICENSE = GPLv2+
 UPX_LICENSE_FILES = COPYING
 
-HOST_UPX_DEPENDENCIES = host-ucl
+HOST_UPX_DEPENDENCIES = host-ucl host-zlib
 
 # We need to specify all, otherwise the default target only prints a message
 # stating to "please choose a target for 'make'"... :-(