spice: fix "info spice"

In case no listening address was specified, "info spice" reports
"0.0.0.0" as address.  Which is incorrect in case spice is listening
on ipv6.  Replace it by a wildcard "*" to indicate it is not limited
to a specific address.

Note:  Being more specific is not possible without extending the
spice-server api.  The socket is handled by spice-server not
qemu, so qemu can't easily figure the actual socket address.
Reported-by: NDavid Jaša <djasa@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

ui/spice-core.c

@@ -532,7 +532,7 @@ SpiceInfo *qmp_query_spice(Error **errp)
     info->auth = g_strdup(auth);
 
     info->has_host = true;
-    info->host = g_strdup(addr ? addr : "0.0.0.0");
+    info->host = g_strdup(addr ? addr : "*");
 
     info->has_compiled_version = true;
     major = (SPICE_SERVER_VERSION & 0xff0000) >> 16;