Is your feature request related to a problem? Please describe.
I am wrapping GHDL in a C application: ghdl_main is called from main. Several C functions are bind to VHDL through VHPIDIRECT, but I believe that this is irrelevant.

The executable is successfully built with ghdl -e. However, when I load it as shared library (e.g., from a Python script), symbols are not found. This is because of /usr/local/lib/ghdl/grt.ver. If I modify it to add the name of the functions that I want to be visible (see #640 (comment)), it works.

I found no option to provide a custom grt.ver script to ghdl -e.

Describe the solution you'd like

I think it would be desirable to provide a script through an arg such as --version-script, in order to avoid multiple users in a system being required to have separate installations of GHDL just to avoid conflicts with this file.

Describe alternatives you've considered

It is possible to work around this issue by using gcc or llvm directly, instead of ghdl -e. As commented in #640, the output of --list-link can be customized through sed. Thus, the version script can be removed, or adapted.

Nonetheless, in the current use case the binary is compiled through VUnit, which is not aware of neither gcc nor llvm. Therefore, I'd like to keep calling ghdl -e, to avoid adding 'compiler support' to VUnit.