[PATCH] [analyzer] Fix inefficiency in dead symbol removal

[Jordan Rose]

  I just had a thought: since every LazyCompoundVal is backed by uniqued LazyCompoundValData, we can just use that as a key in the existing map. Keeps complexity down. What do you think?

  (Oh, and feel free to change the map to a DenseSet if you want. This code predates the introduction of the DenseSet interface.)

http://llvm-reviews.chandlerc.com/D1398