Update vendored library github.com/pkg/xattr

vendor/github.com/pkg/xattr/xattr_linux.go

@@ -32,7 +32,9 @@ func List(path string) ([]string, error) {
 		return nil, &Error{"xattr.List", path, "", err}
 	}
 	if size > 0 {
-		buf := make([]byte, size)
+		// `size + 1` because of ERANGE error when reading
+		// from a SMB1 mount point (https://github.com/pkg/xattr/issues/16).
+		buf := make([]byte, size+1)
 		// Read into buffer of that size.
 		read, err := syscall.Listxattr(path, buf)
 		if err != nil {
@@ -59,3 +61,11 @@ func Remove(path, name string) error {
 	}
 	return nil
 }
+
+// Supported checks if filesystem supports extended attributes
+func Supported(path string) bool {
+	if _, err := syscall.Listxattr(path, nil); err != nil {
+		return err != syscall.ENOTSUP
+	}
+	return true
+}