windows: Support all REPARSE_POINT attrib files properly. (#4203)

This change adopts the upstream fix in this regard at
https://go-review.googlesource.com/#/c/41834/ for Minio's
purposes.

Go's current os.Stat() lacks support for lot of strange
windows files such as

 - share symlinks on SMB2
 - symlinks on docker nanoserver
 - de-duplicated files on NTFS de-duplicated volume.

This PR attempts to incorporate the change mentioned here

   https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/

The article suggests to use Windows I/O manager to
dereference the symbolic link.

Fixes #4122

cmd/update-main.go

@@ -82,7 +82,7 @@ func getCurrentReleaseTime(minioVersion, minioBinaryPath string) (releaseTime ti
 	}
 
 	// Looks like version is minio non-standard, we use minio binary's ModTime as release time.
-	fi, err := os.Stat(minioBinaryPath)
+	fi, err := osStat(minioBinaryPath)
 	if err != nil {
 		err = fmt.Errorf("Unable to get ModTime of %s. %s", minioBinaryPath, err)
 	} else {