PR#6945 and GPR#227: protect Sys and Unix functions against string arguments containing the null character '\000'
PR#6945 and GPR#227: protect Sys and Unix functions against string arguments containing the null character '\000'

Continuation of commit dc043a7.
Fix wrong declaration of cstringvect.

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