unit & shared tests need to run on Windows

[igaw]

The unit tests and shared tests need also to run on Windows.

shared/fs-utils.h should be splitted into a Linux and Windows part.

See my this attempt to get it working: #3678

[bbusacker]

@igaw Trying to assign to @jimmunn but do not have perrms still.

[igaw]

FWIW, we already done some parts of this task. There are two interface which currently not enabled/tested on Windows. The first one is the ini parser. The issue is in the test case where a TMP dir is used, is hard coded. This is breaking on Windows. I think the best way forward is to add additional fs-util.h interfaces for handling TMP dirs and update the test case accordingly. We might need this new interface for other places too.

The other one is the networking interface fs-net.h. Since this for fabrics only, I'd leave it away.

We could add stuff like

#if defined(_WIN32)
#include <direct.h>
#include <io.h>
#define rmdir _rmdir
#define close _close
#define unlink _unlink

to fs-util.h, so we don't have the ifdefery in the code base except in shared.