Update to ver 0.20

Note I have no way of checking if
# FIXME: /usr/bin/spice-client-glib-usb-acl-helper should be installed u+s, see bnc#744251.

is possible to fix, as this bug is not open for the general public

And further: This lint note needs action I guess

spice-gtk.x86_64: I: polkit-untracked-privilege org.spice-space.lowlevelusbaccess (auth_admin:no:auth_admin)
The privilege is not listed in /etc/polkit-default-privs.* which makes it
harder for admins to find. If the package is intended for inclusion in any
SUSE product please open a bug report to request review of the package by the
security team

spice-gtk.x86_64: I: polkit-cant-acquire-privilege org.spice-space.lowlevelusbaccess (auth_admin:no:auth_admin)
Usability can be improved by allowing users to acquire privileges via
authentication. Use e.g. 'auth_admin' instead of 'no' and make sure to define
'allow_any'. This is an issue only if the privilege is not listed in /etc
/polkit-default-privs.*
(forwarded request 181491 from Zaitor)