Implement System for Win32

[neatorobito]

Pretty simple implementation of the hostname and cpu count functions.

[Sija]

crystal tool format please

[straight-shoota]

Please take a look at https://github.com/crystal-lang/crystal/wiki/Porting-to-Windows#bindings for naming in C bindings.

Also, you should put them in a file with the same file name as the C header filer (just with .cr extension). Ditto for the other features in this file.

[neatorobito]

I think I hit all the PR comments with fixes in the latest push. Let me know if there's anything else.

[straight-shoota]

@markrjr This PR needs to address the review comments.

[neatorobito]

I've got most of it done locally, but have not had time to finish the last bits. I'll commit by the end of the week.

[straight-shoota]

Looks great, @markrjr !

It still needs to be integrated with src/crystal/system.cr. Something like this:

{% if flag?(:unix) %}
  require "./system/unix/hostname"

  {% if flag?(:freebsd) || flag?(:openbsd) %}
  require "./system/unix/sysctl_cpucount"
  {% else %}
    require "./system/unix/sysconf_cpucount"
  {% end %}
{% elsif flag?(:win32) %}
  require "./system/win32/hostname"
  require "./system/win32/cpucount"
{% else %}
  {% raise "No Crystal::System implementation available" %}
{% end %}

Specs would be nice. Unfortunately, Process is not yet ported to win32 so it's currently not possible to shell out to retrieve verification values in system_spec.cr.

As a workaround, the commands can be executed as macros. This means the spec will only pass when executed on the same machine as it was compiled. This works on WSL, but not when cross-compiling from a different machine. Such a hack should be put into the PR, but it serves for manual verification.

Once Process is ported, shelling out to hostname should just work on windows as well.

On windows, the cpu count is actually available as environment variable NUMBER_OF_PROCESSORS. The cpu count spec could already be adjusted to use that env var for verification.

[neatorobito]

Is there anything else to tackle here? @RX14 @straight-shoota @r00ster91

[neatorobito]

Neat! 🎉I will do a bit more of a dive into the language before I submit another PR, but thanks for all the help everyone!

[straight-shoota]

@markrjr You're initial patch wasn't bad. Keep it on! =)

[sdogruyol]

Thanks for the great first patch @markrjr 🎉