Rollup merge of #115563 - krasimirgg:llvm-18-bitcodereader, r=nikic

llvm-wrapper: adapt for LLVM API change

No functional changes intended.

Adapts the wrapper for llvm/llvm-project@bbe8cd1.

Found by our experimental rust + llvm @ HEAD CI: https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/22055#018a6495-8dd9-41df-9381-5e7b0009ce0a/274-575

Author: matthiaskrgr