vendor: update buildkit to master@9624ab4

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/containerd/continuity/fs/time.go

@@ -0,0 +1,29 @@
+/*
+   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 fs
+
+import "time"
+
+// Gnu tar and the go tar writer don't have sub-second mtime
+// precision, which is problematic when we apply changes via tar
+// files, we handle this by comparing for exact times, *or* same
+// second count and either a or b having exactly 0 nanoseconds
+func sameFsTime(a, b time.Time) bool {
+	return a == b ||
+		(a.Unix() == b.Unix() &&
+			(a.Nanosecond() == 0 || b.Nanosecond() == 0))
+}