The patch has been revised because minor issues were identified during further testing
verilog: add support to use external vpp library
Install xspice/cmpp, as it may be required by external packages.
See https://der-b.com/posts/2020-04-11-building-a-xspice-codemodel-outside-of-the-ngspice-source-code for example, that cmpp is required outside ngspice.
When testing the patches for using the vvp library at the beginning of the year I got an example using a d_clock binary, which showed this issue; I need to reinvestigate the details.
I fixed the issue.
Add command line support for the 'version [-s|-f]' command
It should be based on git master branch ?