SelectionDAG: Remove unnecessary uses of TargetLowering::getPointerTy()

SelectionDAG: Remove unnecessary uses of TargetLowering::getPointerTy()

If we have a binary operation like ISD:ADD, we can set the result type
equal to the result type of one of its operands rather than using
TargetLowering::getPointerTy().

Also, any use of DAG.getIntPtrConstant(C) as an operand for a binary
operation can be replaced with:
DAG.getConstant(C, OtherOperand.getValueType());

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189227 91177308-0d34-0410-b5e6-96231b3b80d8