vendor: update buildkit to 539be170

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

vendor/go.opentelemetry.io/otel/error_handler.go

@@ -25,3 +25,14 @@ type ErrorHandler interface {
 	// DO NOT CHANGE: any modification will not be backwards compatible and
 	// must never be done outside of a new major release.
 }
+
+// ErrorHandlerFunc is a convenience adapter to allow the use of a function
+// as an ErrorHandler.
+type ErrorHandlerFunc func(error)
+
+var _ ErrorHandler = ErrorHandlerFunc(nil)
+
+// Handle handles the irremediable error by calling the ErrorHandlerFunc itself.
+func (f ErrorHandlerFunc) Handle(err error) {
+	f(err)
+}