lxc: add gnu-tar as a depends to fix lxc-create

lxc: add gnu-tar as a depends to fix lxc-create

Add gnu-tar as a dependency for lxc-create which is needed to
properly extract the root file system tarball. Without it,
symlink target of /bin/tar is busybox and it lacks proper
support to extract with xattrs.  The default gnu-tar is actually
built without this support as well, but it is able to extract
the rootfs tarballs with a warning not an error which is not the
case with busybox which ends in an error.

Signed-off-by: John Audia <redacted>
Build system: x86/64
Build-tested: x86/64/AMD Cezanne
Run-tested: x86/64/AMD Cezanne