See qemu_spice_add_display_interface(), the console index is also used
as channel id.  So put that into the qxl->id field too.

In typical use cases (one primary qxl-vga device, optionally one or more
secondary qxl devices, no non-qxl display devices) this doesn't change
anything.

With this in place the qxl->id can not be used any more to figure
whenever a given device is primary (with vga compat mode) or secondary.
So add a bool to track this.

Cc: spice-devel@lists.freedesktop.org
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Message-id: 20181012114540.27829-1-kraxel@redhat.com