Windows process launch and glob expansion

[rjbou]

If a command contains a glob, the result is not the same on Unix and Windows machines.
Even if i spotted it first on reftest, it hits also opam exec:
On Unix, bash shell

$ ls c* 
config.log  config.status  configure  configure.ac
$ ls 'c*' 
ls: cannot access 'c*': No such file or directory
$ opam exec -- ls c*
config.log  config.status  configure  configure.ac
> opam exec -- ls 'c*'
ls: cannot access 'c*': No such file or directory

On Windows, Cygwin shell

$ ls c*
config.log  config.status  configure  configure.ac

$ ls 'c*'
ls: cannot access 'c*': No such file or directory

$ opam exec -- ls c*
config.log  config.status  configure  configure.ac

$ opam exec -- ls 'c*'
CHANGES  CODE_OF_CONDUCT.md  CONTRIBUTING.md  config.log  config.status  configure  configure.ac

On our Cygwin create process, we use OCaml win_create_process* that perform a glob expansion.