core: Add ot_util_variant_take_ref for older GLib versions

libostree/ostree-core.c

@@ -358,7 +358,7 @@ ostree_parse_metadata_file (const char                  *path,
 
   ret = TRUE;
   *out_type = ret_type;
-  *out_variant = g_variant_take_ref (ret_variant);
+  *out_variant = ot_util_variant_take_ref (ret_variant);
   ret_variant = NULL;
  out:
   if (ret_variant)

libotutil/ot-variant-utils.c

@@ -75,6 +75,18 @@ ot_util_variant_save (GFile *dest,
   return ret;
 }
 
+GVariant *
+ot_util_variant_take_ref (GVariant *variant)
+{
+#if GLIB_CHECK_VERSION(2,32,0)
+  return g_variant_take_ref (variant);
+#else
+  if (g_variant_is_floating (variant))
+    return g_variant_ref_sink (variant);
+  return variant;
+#endif
+}
+
 gboolean
 ot_util_variant_map (GFile *src,
                      const GVariantType *type,

libotutil/ot-variant-utils.h

@@ -28,6 +28,8 @@ G_BEGIN_DECLS
 
 GHashTable *ot_util_variant_asv_to_hash_table (GVariant *variant);
 
+GVariant * ot_util_variant_take_ref (GVariant *variant);
+
 gboolean ot_util_variant_save (GFile *dest,
                                GVariant *variant,
                                GCancellable *cancellable,