lavc/tiff: add GeoTIFF support to the TIFF decoder

      Work done for SOCIS 2011.

See thread:
Subject: [libav-devel] [PATCH 2/3] tiff: Add GeoTIFF support to the TIFF decoder
Date: Tue,  4 Oct 2011 00:19:52 +0200

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>