SPDX Comments for Benchmarks

[jckreg]

Problem

SVCOMP requires SPDX comments

Goal

Add SPDX comments to generated benchmarks with the SVCOMP target.

Autogenerate SPDX comments for future benchmarks using the argv-transformer tool

[swflint]

See https://gitlab.com/sosy-lab/benchmarking/sv-benchmarks/-/blob/main/CONTRIBUTING.md?ref_type=heads#license for requirements.

[swflint]

To expand on this, implementation of this should use the GitHub API at download time to collect license and other metadata, and filter to an approved list of licenses. I will follow-up with two additional issues related to this.