lib: Remove osutil.Remove & osutil.RemoveAll (fixes #3513)

These are no longer required with Go 1.7. Change made by removing the
functions, doing a global s/osutil.Remove/os.Remove/.

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3514

lib/osutil/osutil.go

@@ -15,7 +15,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
-	"syscall"
 
 	"github.com/calmh/du"
 	"github.com/syncthing/syncthing/lib/sync"
@@ -93,93 +92,6 @@ func InWritableDir(fn func(string) error, path string) error {
 	return fn(path)
 }
 
-// Remove removes the given path. On Windows, removes the read-only attribute
-// from the target prior to deletion.
-func Remove(path string) error {
-	if runtime.GOOS == "windows" {
-		info, err := os.Stat(path)
-		if err != nil {
-			return err
-		}
-		if info.Mode()&0200 == 0 {
-			os.Chmod(path, 0700)
-		}
-	}
-	return os.Remove(path)
-}
-
-// RemoveAll is a copy of os.RemoveAll, but uses osutil.Remove.
-// RemoveAll removes path and any children it contains.
-// It removes everything it can but returns the first error
-// it encounters.  If the path does not exist, RemoveAll
-// returns nil (no error).
-func RemoveAll(path string) error {
-	// Simple case: if Remove works, we're done.
-	err := Remove(path)
-	if err == nil || os.IsNotExist(err) {
-		return nil
-	}
-
-	// Otherwise, is this a directory we need to recurse into?
-	dir, serr := os.Lstat(path)
-	if serr != nil {
-		if serr, ok := serr.(*os.PathError); ok && (os.IsNotExist(serr.Err) || serr.Err == syscall.ENOTDIR) {
-			return nil
-		}
-		return serr
-	}
-	if !dir.IsDir() {
-		// Not a directory; return the error from Remove.
-		return err
-	}
-
-	// Directory.
-	fd, err := os.Open(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			// Race. It was deleted between the Lstat and Open.
-			// Return nil per RemoveAll's docs.
-			return nil
-		}
-		return err
-	}
-
-	// Remove contents & return first error.
-	err = nil
-	for {
-		names, err1 := fd.Readdirnames(100)
-		for _, name := range names {
-			err1 := RemoveAll(path + string(os.PathSeparator) + name)
-			if err == nil {
-				err = err1
-			}
-		}
-		if err1 == io.EOF {
-			break
-		}
-		// If Readdirnames returned an error, use it.
-		if err == nil {
-			err = err1
-		}
-		if len(names) == 0 {
-			break
-		}
-	}
-
-	// Close directory, because windows won't remove opened directory.
-	fd.Close()
-
-	// Remove directory.
-	err1 := Remove(path)
-	if err1 == nil || os.IsNotExist(err1) {
-		return nil
-	}
-	if err == nil {
-		err = err1
-	}
-	return err
-}
-
 func ExpandTilde(path string) (string, error) {
 	if path == "~" {
 		return getHomeDir()