ui/spice-display.c: add missing initialization for valgrind

We can't initialize QXLDevSurfaceCreate field by field because it has a
pa hole, and so 4 bytes remain uninitialized when building on x86-64, so
just memset.

Signed-off-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/spice-display.c

@@ -244,6 +244,8 @@ void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd)
 {
     QXLDevSurfaceCreate surface;
 
+    memset(&surface, 0, sizeof(surface));
+
     dprint(1, "%s: %dx%d\n", __FUNCTION__,
            ds_get_width(ssd->ds), ds_get_height(ssd->ds));