[gnome-shell] st: Add missing END_DECLS marker

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0b72ff189652911d8101c2042c6834424b982a4d
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Apr 8 18:02:56 2019 +0200

    st: Add missing END_DECLS marker
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/485

 src/st/st-settings.h | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/st/st-settings.h b/src/st/st-settings.h
index a57885c40..106000168 100644
--- a/src/st/st-settings.h
+++ b/src/st/st-settings.h
@@ -31,4 +31,6 @@ G_DECLARE_FINAL_TYPE (StSettings, st_settings, ST, SETTINGS, GObject)
 
 StSettings * st_settings_get (void);
 
+G_END_DECLS
+
 #endif /* __ST_SETTINGS_H__ */