add zarith 1.13 release

[hannesm]

fixes #5

[hannesm]

Hm, the CI is failing, but from the log I can't figure out what is actually going wrong? Any clues about that?

[hannesm]

debugging shows the error in zarith's configure:

+ ocamlc -custom -ccopt -L/src/_build/solo5/duniverse/Zarith/../../../install/solo5/lib/gmp/  tmp.ml -cclib -lgmp -o tmp.out
/usr/bin/ld: /src/_build/solo5/duniverse/Zarith/../../../install/solo5/lib/gmp//libgmp.so: file not recognized: file truncated
collect2: error: ld returned 1 exit status
File "tmp.ml", line 1:
Error: Error while building custom runtime system

I am now trying to revert the specific zarith commit, and go back to use $cc instead of $ocamlc. Another path may be to teach zarith to use our own (ocaml-solo5) ocamlc toolchain!?

let's take it how it is: our libgmp.so is an empty file, we're only doing statically linked builds anyways...

[hannesm]

ok, this is good for review and merge once CI passes. I avoided the issue above and re-released the package.

[hannesm]

CI is green \o/

[dinosaure]

Thanks!