[PATCH] Add multiple inclusion guards to useldt.h

[Roland McGrath]

> >From reading the code, I believe i686 --with-tls linuxthreads
> are now broken.

Ack!  You're right.  The report was about i586 being broken, and I tested
that and failed to go back and test the i686 build.  It's even worse than
you thought, though!  useldt.h gets included once before USE_TLS is set and
once after, changing how it defines things.  So plain multiple inclusion
protection would in fact break it.  I put in another tweak and now I think
both builds are ok again.


Thanks,
Roland