The Xen toolstack `vncpasswd` guest configuration option depends on QEMU
being built with an external crypto library as of QEMU commit:
21407ddf967f crypto: delete built-in DES implementation
Introduce a dependency of the xen-tools package on gnutls, so that the
option continues to work as expected. Otherwise when attempting to use
`vncpasswd` option guest creation fails due to QEMU not starting.
Reported by: Subbsd <subbsd@gmail.com>
Sponsored by: Cloud Software Group
Approved by: bapt (implicit)
d94cb88a40