testsuite: attempt to make unwind's linker-version test portable
testsuite: attempt to make unwind's linker-version test portable

eliberis/ocaml,msprotz/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,yunxing/ocaml,msprotz/ocaml,yunxing/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,eliberis/ocaml,yunxing/ocaml