r235050 dropped the inlined-at field from `MDLocalVariable`, deferring
to the `!dbg` attachments. Fix `UserValue` to take the `!dbg` into
account when differentiating between variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235140 91177308-0d34-0410-b5e6-96231b3b80d8