Use llvm::BitVector instead of managing memory by hand.  - As it happens, this also fixes a use-of-uninitialized memory that was causing    non-deterministic test failures.
Use llvm::BitVector instead of managing memory by hand.
 - As it happens, this also fixes a use-of-uninitialized memory that was causing
   non-deterministic test failures.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@76857 91177308-0d34-0410-b5e6-96231b3b80d8

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