opkg: add missing dependency on libarchive

opkg requires libarchive. This was expressed in the Config.in file with a
select, but not in the .mk file.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/opkg/opkg.mk

@@ -8,7 +8,7 @@ OPKG_VERSION = v0.3.1
 OPKG_SITE = http://git.yoctoproject.org/git/opkg
 OPKG_SITE_METHOD = git
 # Uses PKG_CHECK_MODULES() in configure.ac
-OPKG_DEPENDENCIES = host-pkgconf
+OPKG_DEPENDENCIES = host-pkgconf libarchive
 OPKG_LICENSE = GPLv2+
 OPKG_LICENSE_FILES = COPYING
 OPKG_INSTALL_STAGING = YES