[llvm-wrapper] adapt for LLVM API change Adapt for the LLVM API changes from 721f975d35. Found via our experimental rust + llvm @ HEAD bot: https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/15203#0184ae73-5169-4b9b-92f4-d4e6e9b86ad9/194-531
721f975d35