Add support for x86-lynxos cross debugger (as bareboard x86).

Add support for x86-lynxos cross debugger (as bareboard x86).

This is a fairly simple patch that we have had for a while.  LynxOS has
relatively few features, from a GDB perspective, and we've been using
a bareboard x86 debugger as our LynxOS cross-debugger.  So here is a patch
that make x86-lynxos an alias of bareboard x86.

On the other end of things, I'm still working on gdbserver support
for LynxOS - I'm just lacking the time to make significant progress.
But this is in the works (in the meantime, we're using gdbserver from
gdb-6.8 which is derived work from LinuxWorks' patch).

I wasn't sure whether this would be interesting or not for the FSF tree,
but since it's simple and unintrusive, I am suggesting it now... Any
objection?  I wasn't sure whether it warranted a NEWS entry either, since
it doesn't really add a new port, just an alias.  I suggest the NEWS entry
when I'm finally done with the gdbserver port.

gdb/ChangeLog:

        * configure.tgt: Treat x86-lynxos targets as x86 bareboard targets
        in terms of configuration.