Generate VCD file for each cover statement

[ShashankVM]

Fixes #1287

[ShashankVM]

Hi Project Maintainers!

I've been using EBMC for hobby projects for a year now. The VCD file generation for each cover statement was a feature that I sorely missed in my projects.

I've implemented this feature and verified it is working locally. I've attached the screenshot of the results.

I'm looking forward to contributing to this project and welcome feedback!

[kroening]

This regresses on the current behavior, where you can get the trace in a file named as the argument of --vcd. The user still needs to give an argument to the --vcd switch, which will be ignored.

[ShashankVM]

Thanks for your feedback. @kroening

Do we want to keep the argument for VCD filename?

If yes, I can include the filename argument as a suffix in the final filename.

If not, I can work on modifying the command line parsing logic. Please let me know how to proceed.

[kroening]

Thanks for your feedback. @kroening

Do we want to keep the argument for VCD filename?

If yes, I can include the filename argument as a suffix in the final filename.

This is what we are doing for --random-traces (look at random_traces.cpp, line 169).

However, making that change would still regress the current behaviour. I am not opposed to this in principle, but we'd need to do this as part of a major version release. Let's do it.