AMDGPU/SI: Do not insert EndCf in an unreachable block

Reviewers:
  arsenm

Differential Revision:
  http://reviews.llvm.org/D22025

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297243 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed