utils: add necessary header and footer to have right calling convention

with c++ code

diff --git a/libgsignon-glib/signon-utils.h b/libgsignon-glib/signon-utils.h
index dec722c..d7d5eca 100644 (file)
--- a/libgsignon-glib/signon-utils.h
+++ b/libgsignon-glib/signon-utils.h
@@ -28,6 +28,8 @@
 
 #include <glib-object.h>
 
+G_BEGIN_DECLS
+
 #define SIGNON_IS_NOT_CANCELLED(error) \
         (error == NULL || \
         error->domain != G_IO_ERROR || \
@@ -40,4 +42,6 @@ void signon_gvalue_free (gpointer val);
 GHashTable *signon_hash_table_from_variant (GVariant *variant);
 GVariant *signon_hash_table_to_variant (GHashTable *hash_table);
 
+G_END_DECLS
+
 #endif //_SIGNON_UTILS_H_