[gnome-builder] flatpak: use IDE_FALLTHROUGH to silence warning

[Christian Hergert <chergert src gnome org>]

commit 3791f486e7e5cc725c3346f22b376981845dcf6e
Author: Christian Hergert <chergert redhat com>
Date:   Thu Mar 16 14:06:32 2017 -0700

    flatpak: use IDE_FALLTHROUGH to silence warning

 .../flatpak/gbp-flatpak-configuration-provider.c   |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/plugins/flatpak/gbp-flatpak-configuration-provider.c 
b/plugins/flatpak/gbp-flatpak-configuration-provider.c
index 7e3ae86..d28611f 100644
--- a/plugins/flatpak/gbp-flatpak-configuration-provider.c
+++ b/plugins/flatpak/gbp-flatpak-configuration-provider.c
@@ -720,6 +720,7 @@ gbp_flatpak_configuration_provider_manifest_changed (GbpFlatpakConfigurationProv
           g_free (filename);
         new_config_file = other_file;
         /* Don't break so we can reuse the code below to add the new config */
+      IDE_FALLTHROUGH;
     case G_FILE_MONITOR_EVENT_CREATED:
     case G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT:
     case G_FILE_MONITOR_EVENT_MOVED_IN: