[IPO] Temporarily rollback r307215.

[GlobalOpt] Remove unreachable blocks before optimizing a function.
While the change is presumably correct, it exposes a latent bug
in DI which breaks on of the CFI checks. I'll analyze it further
and try to understand what's going on.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307729 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed