[PATCH] Add missing include to posix/tst-dir.c

[Florian Weimer]

* Tulio Magno Quites Machado Filho:

> A recent change to posix/tst-dir.c started to use macros from
> libc-internal.h but didn't include it, causing build issues.
>
> 2016-02-22  Tulio Magno Quites Machado Filho  <tuliom@linux.vnet.ibm.com>
>
> 	* posix/tst-dir.c: Include libc-internal.h.

I have never seen a need to include <libc-internal.h> like this
before.  How are you building the tests that you need this?

Thanks,
Florian