[RS6000] Use config/linux.h for powerpc*-*-linux*

[Alan Modra]

On Mon, Nov 26, 2018 at 05:16:38PM -0600, Segher Boessenkool wrote:
> On Mon, Nov 12, 2018 at 09:56:37PM +1030, Alan Modra wrote:
> > Using the macros in config/linux.h rather than duplicating them helps
> > stop future bitrot, and repairs existing bitrot (4 choices for libc in
> > linux.h, fewer in the rs6000 files not that it matters much).  Also
> > fixes the fact that __gnu_linux__ was always defined rather than just
> > when glibc was the libc of choice.
> 
> Sorry for the slow review.  This is okay for trunk.  Thanks!

Thanks, committed revision 266493.

-- 
Alan Modra
Australia Development Lab, IBM