[goffice] Debug improvement

[Morten Welinder <mortenw src gnome org>]

commit 5902592aacde97db6ab8efacf28a4d988457e3fe
Author: Morten Welinder <terra gnome org>
Date:   Fri May 25 09:33:16 2018 -0400

    Debug improvement

 goffice/app/go-plugin.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/goffice/app/go-plugin.c b/goffice/app/go-plugin.c
index 910ba7f1..df3e054e 100644
--- a/goffice/app/go-plugin.c
+++ b/goffice/app/go-plugin.c
@@ -154,6 +154,9 @@ static GObjectClass *parent_class = NULL;
 
 static void plugin_dependency_free (gpointer data);
 
+static void go_plugin_message (gint level, gchar const *format, ...)
+       G_GNUC_PRINTF (2, 3);
+
 static void
 go_plugin_message (gint level, gchar const *format, ...)
 {