It is possible to craft a TIFF document where the IFD list is circular,
leading to an infinite loop while traversing the chain. The libtiff
directory reader has a failsafe that will break out of this loop after
reading 65535 directory entries, but it will continue processing,
consuming time and resources to process what is essentially a bogus TIFF
document.

This change fixes the above behavior by breaking out of processing when
a TIFF document has >= 65535 directories and terminating with an error.