Turn on posix directory for RTEMS

[Jeff Johnston]

Joel Sherrill wrote:
> Hi Jeff,
>
> You and I discussed this a week or two ago and here
> is the patch.  We had stubs for the exec* routines and
> a copy of the *dir routines from around newlib 1.8.
> After this is merged and Ralf turns the crank for
> new RTEMS gcc/newlib RPMs with this, we can
> delete some files from RTEMS.  :)
>
> 2008-11-05  Joel Sherrill <joel.sherrill@oarcorp.com>
>
>    * configure.host: RTEMS now uses posix subdirectory.
>
Patch checked in.  Sorry for the delay.

-- Jeff J.