That solved it. I downloaded the LibXSLT module and recompiled it for my system instead of the cpan packaged binary. My old polymake binary works now too. Curiously enough, I only needed to recompile XML-LibXSLT.
I had some problems running Polymake after a system update, so I tried to compile the latest version from the git repo. Now I have this error: checking perl module XML::LibXSLT ... LibXSLT.c: loadable library and perl binaries are mismatched (got handshake key 0xdb00080, needed 0xdb80080) Some syste...