[yelp] Add G_GNUC_PRINTF attribute to yelp_debug()

[David King <davidk src gnome org>]

commit 48bb6d9c472c0f88731d3d9b04da108b9cdcccdb
Author: David King <amigadave amigadave com>
Date:   Mon Jan 21 14:18:41 2019 +0000

    Add G_GNUC_PRINTF attribute to yelp_debug()
    
    Silence a compiler warning.

 libyelp/yelp-debug.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/libyelp/yelp-debug.h b/libyelp/yelp-debug.h
index 620a4bf1..6e057d51 100644
--- a/libyelp/yelp-debug.h
+++ b/libyelp/yelp-debug.h
@@ -68,7 +68,8 @@ typedef enum {
 
 G_GNUC_INTERNAL
 void yelp_debug (const gchar *file, guint line, 
-                 const gchar *function, guint flags, const gchar *format, ...);
+                 const gchar *function, guint flags,
+                 const gchar *format, ...) G_GNUC_PRINTF (5, 6);
 
 G_END_DECLS