vendor: update buildkit to v0.17.0-rc2

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

vendor/github.com/containerd/continuity/fs/fstest/mkfs_linux.go

@@ -0,0 +1,44 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fstest
+
+import (
+	"os/exec"
+	"testing"
+
+	"github.com/containerd/continuity/testutil"
+	"github.com/containerd/continuity/testutil/loopback"
+)
+
+func WithMkfs(t *testing.T, f func(), mkfs ...string) {
+	testutil.RequiresRoot(t)
+	mnt := t.TempDir()
+	loop, err := loopback.New(100 << 20) // 100 MB
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer loop.Close()
+	if out, err := exec.Command(mkfs[0], append(mkfs[1:], loop.Device)...).CombinedOutput(); err != nil {
+		t.Fatalf("could not mkfs (%v) %s: %v (out: %q)", mkfs, loop.Device, err, string(out))
+	}
+	if out, err := exec.Command("mount", loop.Device, mnt).CombinedOutput(); err != nil {
+		t.Fatalf("could not mount %s: %v (out: %q)", loop.Device, err, string(out))
+	}
+	defer testutil.Unmount(t, mnt)
+	t.Setenv("TMPDIR", mnt)
+	f()
+}