to MCRegisterInfo. Also initialize the mapping at construction time.
This patch eliminate TargetRegisterInfo from TargetAsmInfo. It's another step
towards fixing the layering violation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135424 91177308-0d34-0410-b5e6-96231b3b80d8