vendor: update buildkit to opentelemetry support

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

vendor/github.com/moby/buildkit/util/tracing/env/traceenv.go

@@ -0,0 +1,54 @@
+package detect
+
+import (
+	"context"
+	"os"
+
+	"github.com/moby/buildkit/util/appcontext"
+	"go.opentelemetry.io/otel/propagation"
+)
+
+const (
+	traceparentHeader = "traceparent"
+	tracestateHeader  = "tracestate"
+)
+
+func init() {
+	appcontext.Register(initContext)
+}
+
+func initContext(ctx context.Context) context.Context {
+	// previously defined in https://github.com/open-telemetry/opentelemetry-swift/blob/4ea467ed4b881d7329bf2254ca7ed7f2d9d6e1eb/Sources/OpenTelemetrySdk/Trace/Propagation/EnvironmentContextPropagator.swift#L14-L15
+	parent := os.Getenv("OTEL_TRACE_PARENT")
+	state := os.Getenv("OTEL_TRACE_STATE")
+
+	if parent == "" {
+		return ctx
+	}
+
+	tc := propagation.TraceContext{}
+	return tc.Extract(ctx, &textMap{parent: parent, state: state})
+}
+
+type textMap struct {
+	parent string
+	state  string
+}
+
+func (tm *textMap) Get(key string) string {
+	switch key {
+	case traceparentHeader:
+		return tm.parent
+	case tracestateHeader:
+		return tm.state
+	default:
+		return ""
+	}
+}
+
+func (tm *textMap) Set(key string, value string) {
+}
+
+func (tm *textMap) Keys() []string {
+	return []string{traceparentHeader, tracestateHeader}
+}