[SeparateConstOffsetFromGEP] Preserve metadata when splitting GEPs

Summary:
!amdgpu.uniform needs to be preserved for AMDGPU, otherwise bad things
happen.

Reviewers: arsenm, nhaehnle, jingyue, broune, majnemer, bjarke.roune, dblaikie

Subscribers: wdng, tpr, llvm-commits

Differential Revision: https://reviews.llvm.org/D42744

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323907 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed