LibIPC: Port to Windows

[stasoid]

Requires #2673 #2674 #2946

[stasoid]

I changed the order of declarations, which makes the diff unreadable. This is a diff that shows changes of substance (without reordering or inline removing).

[stasoid]

@R-Goc @konradekk Please don't comment on my PRs. I am only interested in reviews from maintainers. So far your comments provided very little value for me.

I thought I can just ignore your comments, but Jelle Raaijmakers says unresolved comments may be the reason why my PR is not getting a review from maintainers, so I am asking not to spam here.

I am marking all conversations as resolved now to increase my chances for a review from maintainers.

[stasoid]

I found a problem with the handling of sockets. When given a socket fd, _close does not call closesocket, it calls CloseHandle. But the doc for CloseHandle specifically says that CloseHandle should not be used for sockets. So WIN32 APIs behave inconsistently here. If _close cannot properly handle socket fds why _open_osfhandle works for socket handles? It should fail as it does for file mapping handles.

This cannot be fixed just by adding if (is_socket(fd)) closesocket(_get_osfhandle(fd)); to System::close because fd might be created with _dup, and, given above, I presume _dup doesn't properly duplicate sockets either (it is likely just duplicates the handles, not additional socket state).

So I am marking this as draft for now.

[stasoid]

To fix the problem above, I now treat socket handles the same as file mapping handles. I.e. using pseudo file descriptor instead of calling _open_osfhandle, see #2946.