SimplifyCFG.cpp: Tweak to let msc17 compliant.

  - Use LLVM_DELETED_FUNCTION.
  - Don't use member initializers.
  - Don't use initializer list.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222422 91177308-0d34-0410-b5e6-96231b3b80d8