[gimp] libgimp: need to cast GimpMetadata when calling GExiv2Metadata API

[Michael Natterer <mitch src gnome org>]

commit eeebd98005deb6e6a41776d23e56d678c7e16a11
Author: Michael Natterer <mitch gimp org>
Date:   Mon Feb 20 01:30:19 2017 +0100

    libgimp: need to cast GimpMetadata when calling GExiv2Metadata API

 libgimp/gimpimagemetadata.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/libgimp/gimpimagemetadata.c b/libgimp/gimpimagemetadata.c
index 983ba7a..bde4d90 100644
--- a/libgimp/gimpimagemetadata.c
+++ b/libgimp/gimpimagemetadata.c
@@ -775,7 +775,8 @@ gimp_image_metadata_rotate_query (gint32        image_ID,
   g_free (parasite_name);
 
   gimp_image_metadata_rotate (image_ID, orientation);
-  gexiv2_metadata_set_orientation (metadata, GEXIV2_ORIENTATION_NORMAL);
+  gexiv2_metadata_set_orientation (GEXIV2_METADATA (metadata),
+                                   GEXIV2_ORIENTATION_NORMAL);
 }
 
 static gboolean