Minor polishing of VTableBuilder

[Timur Iskhodzhanov]

2013/5/13 Anders Carlsson <andersca at icloud.com>:
> sorry for not getting back to you earlier. It's been a long time since I wrote this VTable code and I'd have
> to page everything in again. I'll try to look at your patch this weekend.

Thanks!
If you have limited time on the weekend, I'd prefer if you looked at
http://llvm-reviews.chandlerc.com/D785 instead as my further work
somewhat depends on D785 and also D785 answers a couple of questions
asked in vtables_comments_2.patch

--
Timur