Add libexif to deps/third_party.

libexif/sources/libexif/exif-ifd.h

+/* exif-ifd.h
+ *
+ * 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 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, 
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of 
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details. 
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301  USA.
+ */
+
+#ifndef __EXIF_IFD_H__
+#define __EXIF_IFD_H__
+
+/*! Possible EXIF Image File Directories */
+typedef enum {
+        EXIF_IFD_0 = 0,                /*!< */
+        EXIF_IFD_1,                    /*!< */
+        EXIF_IFD_EXIF,                 /*!< */
+        EXIF_IFD_GPS,                  /*!< */
+        EXIF_IFD_INTEROPERABILITY,     /*!< */
+        EXIF_IFD_COUNT                 /*!< Not a real value, just (max_value + 1). */
+} ExifIfd;
+
+/*! Return a textual name of the given IFD. The name is a short, unique,
+ * non-localized text string containing only US-ASCII alphanumeric
+ * characters.
+ *
+ * \param[in] ifd IFD
+ * \return textual name of the IFD
+ */
+const char *exif_ifd_get_name (ExifIfd ifd);
+
+#endif /* __EXIF_IFD_H__ */