Add libexif to deps/third_party.

libexif/sources/libexif/exif-data-type.h

+/* exif-data-tag.h
+ *
+ * Copyright (c) 2005 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, 
+ * 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_DATA_TYPE_H__
+#define __EXIF_DATA_TYPE_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/*! Represents the type of image data to which the EXIF data applies.
+ * The EXIF tags have different constraints depending on the type of
+ * image data.
+ */
+typedef enum {
+        EXIF_DATA_TYPE_UNCOMPRESSED_CHUNKY = 0,
+        EXIF_DATA_TYPE_UNCOMPRESSED_PLANAR,
+        EXIF_DATA_TYPE_UNCOMPRESSED_YCC,
+        EXIF_DATA_TYPE_COMPRESSED,
+        EXIF_DATA_TYPE_COUNT,
+
+        EXIF_DATA_TYPE_UNKNOWN = EXIF_DATA_TYPE_COUNT
+} ExifDataType;
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* __EXIF_TAG_H__ */