Revert [GlobalOpt] Pass DTU to removeUnreachableBlocks instead of recomputing.
Revert [GlobalOpt] Pass DTU to removeUnreachableBlocks instead of recomputing.

This breaks http://lab.llvm.org:8011/builders/sanitizer-windows/builds/52310

This reverts r373430 (git commit 70f70035484ba199a329f9f8d9bd67e37bc2b408)

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@373432 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm