AMDGPU/SI: Add support for AMD code object version 2.

Summary:
Version 2 is now the default.  If you want to emit version 1, use
the amdgcn--amdhsa-amdcov1 triple.

Reviewers: arsenm, kzhuravl

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D19283

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268647 91177308-0d34-0410-b5e6-96231b3b80d8
15 files changed