Save argument list alloc state by recording it as the operands of Instruction

Save argument list alloc state by recording it as the operands of Instruction
#-1. Other minor changes to deal with AllocInfo.Instruction becoming an int.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12246 91177308-0d34-0410-b5e6-96231b3b80d8