since libc6 in bookworm does not provide use '--enable-obsolete-rpc'
anymore and zfs needs it (building '--without-libtirpc' fails) - we
add it to both images.
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com> Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>