[Mingw-cross-env-list] upgrade to libtiff 4

[Mark Brand]

Hi,

I updated tiff to version 4 on the development branch, but this turned 
out to have consequences I didn't anticipate. This is because this new 
version depends on lzma (xz), but other packages don't expect this and 
generally do not use pkg-config for libtiff. I think I have fixed or 
worked around all the problems in mingw-cross-env's packages, but if you 
run into more problems please let me know.

My apologies if you ran into trouble while I was sorting this out.

Mark