Update rustc_llvm_wrapper to optionally support LLVM v19

[brandonros]

I can't tell for sure but https://github.com/Rust-GPU/Rust-CUDA/tree/main/crates/rustc_codegen_nvvm/rustc_llvm_wrapper seems to be a copy of https://github.com/rust-lang/rust/tree/master/compiler/rustc_llvm

If we are going to actually take a stab at LLVM 19 (similar to #197 but this says LLVM 18... should probably say LLVM 19) we probably need to either

• remove this rustc_llvm_wrapper and replace it with rust/compiler/rustc_llvm/llvm-wrapper equivalent

or

• copy the "more up to date" files into Rust-CDA

given that the current one acts as a bridge to LLVM and is "pinned" to LLVM v7

When trying to just swap it out, you'll get errors that the #include are out of date/moved around, for example

To match the version of nightly we are pinned to:

rustc --version --verbose
rustc 1.87.0-nightly (8c392966a 2025-03-01)
binary: rustc
commit-hash: 8c392966a013fd8a09e6b78b3c8d6e442bc278e1
commit-date: 2025-03-01
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

https://github.com/rust-lang/rust/tree/8c392966a013fd8a09e6b78b3c8d6e442bc278e1/compiler/rustc_llvm