Fixed build constraints for other systems

src/fs/Walk_windows.go

@@ -1,28 +0,0 @@
-//go:build windows
-
-package fs
-
-import "os"
-
-// Walk calls your callback function for every file name inside the directory.
-// It doesn't distinguish between files and directories.
-func Walk(directory string, callBack func(string)) error {
-	f, err := os.Open(directory)
-
-	if err != nil {
-		return err
-	}
-
-	files, err := f.Readdirnames(0)
-	f.Close()
-
-	if err != nil {
-		return err
-	}
-
-	for _, file := range files {
-		callBack(file)
-	}
-
-	return nil
-}