kms-impl-simple: Add fake cursor planes if no real ones

Non-atomic drivers may support drmModeSetCursor() even if no cursor
plane is advertised. To deal with this, add a fake cursor plane for
every CRTC when using MetaKmsImplSimple. This will eventually be
translated to drmModeSetCursor() calls without any explicit cursor plane
usage.

Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/1058

https://gitlab.gnome.org/GNOME/mutter/merge_requests/1079

src/backends/native/meta-kms-impl.c

@@ -71,6 +71,13 @@ meta_kms_impl_dispatch_idle (MetaKmsImpl *impl)
   META_KMS_IMPL_GET_CLASS (impl)->dispatch_idle (impl);
 }
 
+void
+meta_kms_impl_notify_device_created (MetaKmsImpl   *impl,
+                                     MetaKmsDevice *device)
+{
+  META_KMS_IMPL_GET_CLASS (impl)->notify_device_created (impl, device);
+}
+
 static void
 meta_kms_impl_set_property (GObject      *object,
                             guint         prop_id,