vendor: update buildkit to master@ae9d0f5

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/moby/buildkit/util/contentutil/source.go

@@ -0,0 +1,34 @@
+package contentutil
+
+import (
+	"net/url"
+	"strings"
+
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/reference"
+)
+
+func HasSource(info content.Info, refspec reference.Spec) (bool, error) {
+	u, err := url.Parse("dummy://" + refspec.Locator)
+	if err != nil {
+		return false, err
+	}
+
+	if info.Labels == nil {
+		return false, nil
+	}
+
+	source, target := u.Hostname(), strings.TrimPrefix(u.Path, "/")
+	repoLabel, ok := info.Labels["containerd.io/distribution.source."+source]
+	if !ok || repoLabel == "" {
+		return false, nil
+	}
+
+	for _, repo := range strings.Split(repoLabel, ",") {
+		// the target repo is not a candidate
+		if repo == target {
+			return true, nil
+		}
+	}
+	return false, nil
+}