API Change: AnalysisUsage

This is just a note to mention that I just checked in this change (and
fallout from it):

Which renames:
  AnalysisUsage::preservesAll -> getPreservesAll
  AnalysisUsage::preservesCFG -> setPreservesCFG

to be consistent with the already existing setPreservesAll method. This
was a very confusing arrangement that Casey recently pointed out.

I fixed all uses of these that are in the CVS repository. When these
updates reach you, you will have to update any uses of these methods to
call the new name. As always, let me know if you have any questions.