Add support for sparc-wrs-vxworks

[Eric Botcazou]

> Well, the current set-up was the result of this thread:
>
>    http://gcc.gnu.org/ml/gcc/2007-03/msg00043.html
>
> where I tried to find out what the preferred approach would be.  I'm
> happy to reopen the debate if you don't like it.

I don't, but it's OK for the sake of consistency.

> It sounds from the above like you'd prefer all SPARC ports to include
> vxworks-dummy.h in tm_file, is that right?

That would probably be worse. :-)

-- 
Eric Botcazou