Pass the LLVM IR version of argument types down into computeInfo.

Pass the LLVM IR version of argument types down into computeInfo.
This is somewhat annoying to do this at this level, but it avoids
having ABIInfo know depend on CodeGenTypes for a hint.

Nothing is using this yet, so no functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107111 91177308-0d34-0410-b5e6-96231b3b80d8