[CodeGen] fix argument attribute in lowering statepoint/patchpoint

Summary:
Use the correct loop index varaible, ArgI, to retrieve attributes.

Reviewers: thanm, sanjoy, rnk

Reviewed By: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43832

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326433 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed