libarchive: Add PACKAGECONFIG for lz4 to ensure determinism

This avoids:

WARNING: opkg-1_0.3.1-r0 do_package_qa: QA Issue: libopkg rdepends on lz4, but it isn't a build dependency, missing lz4 in DEPENDS or PACKAGECONFIG? [build-deps]

and ERROR:

build-appliance-image-15.0.0-r0 do_rootfs: Unable to install packages. Command '/home/pokybuild/yocto-autobuilder/yocto-worker/build-appliance/build/build/tmp/sysroots/x86_64-linux/usr/bin/smart --log-level=warning --data-dir=/home/pokybuild/yocto-autobuilder/yocto-worker/build-appliance/build/build/tmp/work/qemux86_64-poky-linux/build-appliance-image/15.0.0-r0/rootfs/var/lib/smart install -y packagegroup-core-boot@qemux86_64 packagegroup-core-ssh-openssh@all psplash@core2_64 kernel-dev@qemux86_64 packagegroup-core-x11-base@all kernel-devsrc@qemux86_64 smartpm@core2_64 packagegroup-self-hosted@all rpm@core2_64 locale-base-en-us@core2_64 locale-base-en-gb@core2_64' returned 1:
Loading cache...
Updating cache... ######################################## [100%]

Computing transaction...error: Can't install libopkg1-1:0.3.1-r0.0@core2_64: no package provides lz4 >= 131+git0+d86dc9167

index e1f0202..fe22ea5 100644
@@ -29,6 +29,7 @@ PACKAGECONFIG[libxml2] = "--with-xml2,--without-xml2,libxml2,"
 PACKAGECONFIG[expat] = "--with-expat,--without-expat,expat,"
 PACKAGECONFIG[lzo] = "--with-lzo2,--without-lzo2,lzo,"
 PACKAGECONFIG[nettle] = "--with-nettle,--without-nettle,nettle,"
+PACKAGECONFIG[lz4] = "--with-lz4,--without-lz4,lz4,"
 
 SRC_URI = "http://libarchive.org/downloads/libarchive-${PV}.tar.gz \
            "