Now, things are becoming REALLY confusing. The script does build
pugi, but is never telling OIIO to use an external one. Which makes
it to use a bundled one.
Trying to link OSL to a different version of pugi causes a lot of
linking errors.
Interestingly enough, that was me who made OSL to use external pugi
to solve configuration problem. But now i can not reproduce that
anymore.
Ideally we would either link everything against our pugi, or not
compile it at all.