add kissat support

[tye-singwa]

Hi, this is attempt to add kissat support to pysat
Cannot add some features:

• no incremental support
• no assumptions
• no propagation
  Checked on linux + windows

[alexeyignatiev]

Thanks, @tye-singwa. Looks like it does not pass the CI build tests.

[user202729]

Has been a long time, but this PR causes a segmentation fault for me.

The segmentation fault is in factor.cc

      const unsigned q = quotient_watch.binary.lit;
      watches *q_watches = all_watches + q;
      ticks += 1 + kissat_cache_lines (SIZE_WATCHES (*q_watches),
                                       sizeof (watch));

when q = 2147483647.

(haven't gotten around to create a minimal reproducible example.)

I've no idea what causes this, so I decide to just install standalone kissat and write a plugin that uses write to dimacs (.cnf) format and invoke the executable with subprocess.run.

[alexeyignatiev]

Thanks for checking, @user202729 !