Fetch libexif 0.6.21 to include the security fixes.

libexif/sources/libexif/fuji/mnote-fuji-tag.c

 /* mnote-fuji-tag.c
  *
  * Copyright (c) 2002 Lutz Mueller <lutz@users.sourceforge.net>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful, 
@@ skipping 80 matching lines @@
         return NULL;
 }
 
 const char *
 mnote_fuji_tag_get_description (MnoteFujiTag t)
 {
         unsigned int i;
 
         for (i = 0; i < sizeof (table) / sizeof (table[0]); i++)
                 if (table[i].tag == t) {
-                        if (!*table[i].description)
+                        if (!table[i].description || !*table[i].description)
                                 return "";
 #if defined(BIND_TEXTDOMAIN)
                         bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
 #endif
                         return _(table[i].description);
                 }
         return NULL;
 }