builder: Pass nil linter to instructions.Parse

eea0b41bf4fb1d69e109ff5ff8045c63f0c0d510 added a new argument to
`instructions.Parse` to support issuing linter warnings.

Classic builder uses it to parse the Dockerfile instructions and its
usage needs adjustment.

The classic builder is deprecated and we won't be adding any new
features to it, so we just pass a nil linter callback.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

builder/dockerfile/builder.go

@@ -187,7 +187,7 @@ func buildLabelOptions(labels map[string]string, stages []instructions.Stage) {
 func (b *Builder) build(ctx context.Context, source builder.Source, dockerfile *parser.Result) (*builder.Result, error) {
 	defer b.imageSources.Unmount()
 
-	stages, metaArgs, err := instructions.Parse(dockerfile.AST)
+	stages, metaArgs, err := instructions.Parse(dockerfile.AST, nil)
 	if err != nil {
 		var uiErr *instructions.UnknownInstructionError
 		if errors.As(err, &uiErr) {