[toplevel patch] delete references to tix

[Nathanael Nerode]

>
>The last official release, gdb 5.3 had an Insight that still used tix.  
>I don't recommend this version to Insight users, but I see your point
>about builds.  I guess someone might still need the tix toplevel stuff;
>I just left it in out of laziness and because it didn't affect 
>anything.
>
>Martin

I'll wait until gdb releases.  I haven't been paying enough attention to 
gdb; it's been without tix for long enough I guess I assumed somebody'd 
released. :-)

--Nathanael