Incorporate hardware verification tasks

A new MR !1380 (merged) is created to replace this!

This MR adds 1224 C programs (6 array tasks + 1218 bit-vector tasks) converted by sosy-lab/software/btor2c@bfcfb8b0 from word-level hardware model checking tasks.

Each C program contains the URL to its source, and is under the same license as its original Btor2 file. All tasks assume LP64 data model and are associated with unreach-call property. The programs that contain bugs (reach_error() is reachable) are additionally associated with coverage-error-call property.

728 programs are safe (verdict=true) and 496 are unsafe (verdict=false). The verdict of each task is either known from its source, or determined by the answers returned by hardware model checkers. There are 105 tasks (unknown-tasks.txt) that we do not know the correct verdict (none of the hardware model checkers were able to verify them), so we assume their verdicts are all "true".

Checklist

• programs added to new and appropriately named directory
• license present and acceptable (in machine-readable comment at beginning of program as specified by the REUSE project)
• contributed-by present (either in README file or as comment at beginning of program)
• programs added to a .set file of an existing category, or new sub-category established (if justified)
• suggest to add it to benchmark definitions (.XML) in repositories for benchmark-definitions (see sosy-lab/sv-comp/bench-defs#151 (closed) and sosy-lab/test-comp/bench-defs#4 (closed))
• intended property matches the corresponding .prp file
• programs and expected answer added to a .yml file according to task definitions
• data model present in task-definition file
• [ ] original (ideally not preprocessed) sources present
• [ ] preprocessed files present
• [ ] preprocessed files generated with correct architecture
• Makefile added with correct content and without overly broad suppression of warnings