Compatibility with newer versions of GHDL

[machitgarha]

GHDL 2.0 and 3.0 have been released, and 4.0 is being worked on. Unfortunately, they include some breaking changes with the GHDL command-line that prevents Parvaj working correctly.

There should be a way to detect the GHDL version, and use proper options when invoking it. Or probably, if #3 is implemented, we can do that statically, although implementing it might not be trivial.