vendor: update buildkit with typed errors support

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

vendor/github.com/moby/buildkit/util/progress/multireader.go

@@ -0,0 +1,77 @@
+package progress
+
+import (
+	"context"
+	"io"
+	"sync"
+)
+
+type MultiReader struct {
+	mu          sync.Mutex
+	main        Reader
+	initialized bool
+	done        chan struct{}
+	writers     map[*progressWriter]func()
+}
+
+func NewMultiReader(pr Reader) *MultiReader {
+	mr := &MultiReader{
+		main:    pr,
+		writers: make(map[*progressWriter]func()),
+		done:    make(chan struct{}),
+	}
+	return mr
+}
+
+func (mr *MultiReader) Reader(ctx context.Context) Reader {
+	mr.mu.Lock()
+	defer mr.mu.Unlock()
+
+	pr, ctx, closeWriter := NewContext(ctx)
+	pw, _, ctx := FromContext(ctx)
+
+	w := pw.(*progressWriter)
+	mr.writers[w] = closeWriter
+
+	go func() {
+		select {
+		case <-ctx.Done():
+		case <-mr.done:
+		}
+		mr.mu.Lock()
+		defer mr.mu.Unlock()
+		delete(mr.writers, w)
+	}()
+
+	if !mr.initialized {
+		go mr.handle()
+		mr.initialized = true
+	}
+
+	return pr
+}
+
+func (mr *MultiReader) handle() error {
+	for {
+		p, err := mr.main.Read(context.TODO())
+		if err != nil {
+			if err == io.EOF {
+				mr.mu.Lock()
+				for w, c := range mr.writers {
+					w.Close()
+					c()
+				}
+				mr.mu.Unlock()
+				return nil
+			}
+			return err
+		}
+		mr.mu.Lock()
+		for _, p := range p {
+			for w := range mr.writers {
+				w.writeRawProgress(p)
+			}
+		}
+		mr.mu.Unlock()
+	}
+}