tests: avoid spurious mkdir/selinux test failure on HP-UX 11.23

* tests/mkdir/selinux: Accept yet another diagnostic.
Reported by Matthew Woehlke.

tests/mkdir/selinux

@@ -1,7 +1,7 @@
 #!/bin/sh
 # ensure that an invalid context doesn't cause a segfault
 
-# Copyright (C) 2008 Free Software Foundation, Inc.
+# Copyright (C) 2008-2009 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -44,6 +44,7 @@ for cmd_w_arg in 'mkdir dir' 'mknod b p' 'mkfifo f'; do
   # Some systems fail with ENOTSUP, EINVAL, ENOENT, or even
   # "Unknown system error", or "Function not implemented".
   # For AIX 5.3: "Unsupported attribute value"
+  # For HP-UX 11.23: Unknown error (252)
   sed					\
     -e 's/ Not supported$//'		\
     -e 's/ Invalid argument$//'		\
@@ -51,6 +52,7 @@ for cmd_w_arg in 'mkdir dir' 'mknod b p' 'mkfifo f'; do
     -e 's/ Operation not supported$//'	\
     -e 's/ Function not implemented$//'	\
     -e 's/ Unsupported attribute value$//'	\
+    -e 's/ Unknown error .*$//'	\
     -e 's/ No such file or directory$//' out > k || fail=1
   mv k out || fail=1
   compare out exp || fail=1