[PATCH] [analyzer] Fix handling of "empty" structs with base classes

[Jordan Rose]

  I think this is the commit that's breaking some tests on our internal buildbot, but I'm not sure. I'll look into it.

  (At first I thought it was because you can't ask if there are base classes because the struct might be forward-declared, but then I realized that you couldn't load from it if it were.)

http://llvm-reviews.chandlerc.com/D1547

COMMIT
  http://llvm-reviews.chandlerc.com/rL189590