[PATCH] Prefer /dev/shm over /tmp in utime family tests

[Florian Weimer]

* Adhemerval Zanella via Libc-alpha:

> What instead we make libsupport to use builddir as the temporary base
> directory instead? So all temporary files, directories, pipe, etc. would
> be created and tests against a user-defined directory instead of a system
> one.

It doesn't solve the issue with file system variance.  It's worse than
/tmp because that's more likely to be on tmpfs.  If we move the
directory into the build tree, everyone using XFS (that has the
forgetful VFS bug fixed) will end up with lots of FAILs.

Thanks,
Florian