vendor: update buildkit to opentelemetry support

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/util/tracing/detect/delegated/delegated.go

@@ -0,0 +1,75 @@
+package jaeger
+
+import (
+	"context"
+	"sync"
+
+	"github.com/moby/buildkit/util/tracing/detect"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+const maxBuffer = 256
+
+var exp = &Exporter{}
+
+func init() {
+	detect.Register("delegated", func() (sdktrace.SpanExporter, error) {
+		return exp, nil
+	}, 100)
+}
+
+type Exporter struct {
+	mu        sync.Mutex
+	exporters []sdktrace.SpanExporter
+	buffer    []sdktrace.ReadOnlySpan
+}
+
+var _ sdktrace.SpanExporter = &Exporter{}
+
+func (e *Exporter) ExportSpans(ctx context.Context, ss []sdktrace.ReadOnlySpan) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	var err error
+	for _, e := range e.exporters {
+		if err1 := e.ExportSpans(ctx, ss); err1 != nil {
+			err = err1
+		}
+	}
+	if err != nil {
+		return err
+	}
+
+	if len(e.buffer) > maxBuffer {
+		return nil
+	}
+
+	e.buffer = append(e.buffer, ss...)
+	return nil
+}
+
+func (e *Exporter) Shutdown(ctx context.Context) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	var err error
+	for _, e := range e.exporters {
+		if err1 := e.Shutdown(ctx); err1 != nil {
+			err = err1
+		}
+	}
+
+	return err
+}
+
+func (e *Exporter) SetSpanExporter(ctx context.Context, exp sdktrace.SpanExporter) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	e.exporters = append(e.exporters, exp)
+
+	if len(e.buffer) > 0 {
+		return exp.ExportSpans(ctx, e.buffer)
+	}
+	return nil
+}