[PATCH] [ms-cxxabi] Move VBTableBuilder from CodeGen over to AST/VTableBuilder.cpp

[David Majnemer]

  LGTM.

  I wrote up a bunch of comments but they should be applied to the finished product, not this code re-org.

http://llvm-reviews.chandlerc.com/D2499

BRANCH
  mangle-vbtables

ARCANIST PROJECT
  clang