vendor: update buildkit to v0.18.0-rc1

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

vendor/go.opentelemetry.io/otel/sdk/metric/internal/exemplar/hist.go

@@ -0,0 +1,46 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package exemplar // import "go.opentelemetry.io/otel/sdk/metric/internal/exemplar"
+
+import (
+	"context"
+	"slices"
+	"sort"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Histogram returns a [Reservoir] that samples the last measurement that falls
+// within a histogram bucket. The histogram bucket upper-boundaries are define
+// by bounds.
+//
+// The passed bounds will be sorted by this function.
+func Histogram(bounds []float64) Reservoir {
+	slices.Sort(bounds)
+	return &histRes{
+		bounds:  bounds,
+		storage: newStorage(len(bounds) + 1),
+	}
+}
+
+type histRes struct {
+	*storage
+
+	// bounds are bucket bounds in ascending order.
+	bounds []float64
+}
+
+func (r *histRes) Offer(ctx context.Context, t time.Time, v Value, a []attribute.KeyValue) {
+	var x float64
+	switch v.Type() {
+	case Int64ValueType:
+		x = float64(v.Int64())
+	case Float64ValueType:
+		x = v.Float64()
+	default:
+		panic("unknown value type")
+	}
+	r.store[sort.SearchFloat64s(r.bounds, x)] = newMeasurement(ctx, t, v, a)
+}