vendor: update buildkit to master@ae9d0f5

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

vendor/github.com/prometheus/client_golang/prometheus/internal/metric.go

@@ -19,18 +19,34 @@ import (
 	dto "github.com/prometheus/client_model/go"
 )
 
-// metricSorter is a sortable slice of *dto.Metric.
-type metricSorter []*dto.Metric
+// LabelPairSorter implements sort.Interface. It is used to sort a slice of
+// dto.LabelPair pointers.
+type LabelPairSorter []*dto.LabelPair
 
-func (s metricSorter) Len() int {
+func (s LabelPairSorter) Len() int {
 	return len(s)
 }
 
-func (s metricSorter) Swap(i, j int) {
+func (s LabelPairSorter) Swap(i, j int) {
 	s[i], s[j] = s[j], s[i]
 }
 
-func (s metricSorter) Less(i, j int) bool {
+func (s LabelPairSorter) Less(i, j int) bool {
+	return s[i].GetName() < s[j].GetName()
+}
+
+// MetricSorter is a sortable slice of *dto.Metric.
+type MetricSorter []*dto.Metric
+
+func (s MetricSorter) Len() int {
+	return len(s)
+}
+
+func (s MetricSorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s MetricSorter) Less(i, j int) bool {
 	if len(s[i].Label) != len(s[j].Label) {
 		// This should not happen. The metrics are
 		// inconsistent. However, we have to deal with the fact, as
@@ -68,7 +84,7 @@ func (s metricSorter) Less(i, j int) bool {
 // the slice, with the contained Metrics sorted within each MetricFamily.
 func NormalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
 	for _, mf := range metricFamiliesByName {
-		sort.Sort(metricSorter(mf.Metric))
+		sort.Sort(MetricSorter(mf.Metric))
 	}
 	names := make([]string, 0, len(metricFamiliesByName))
 	for name, mf := range metricFamiliesByName {