vendor: add github.com/a8m/tree

vendor/github.com/a8m/tree/stat_unix.go

@@ -0,0 +1,20 @@
+//+build !plan9,!windows
+
+package tree
+
+import (
+	"os"
+	"syscall"
+)
+
+func getStat(fi os.FileInfo) (ok bool, inode, device, uid, gid uint64) {
+	sys := fi.Sys()
+	if sys == nil {
+		return false, 0, 0, 0, 0
+	}
+	stat, ok := sys.(*syscall.Stat_t)
+	if !ok {
+		return false, 0, 0, 0, 0
+	}
+	return true, uint64(stat.Ino), uint64(stat.Dev), uint64(stat.Uid), uint64(stat.Gid)
+}