Auto merge of #86015 - jyn514:revert-revert, r=Mark-Simulacrum

Move LLVM submodule updates back to native.rs

Time to find more bugs!

The first commit is a straight revert of https://github.com/rust-lang/rust/pull/85647, the second is a fix for https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/x.2Epy.20always.20updates.20LLVM.20submodule/near/240113320 and https://github.com/rust-lang/rust/pull/82653#issuecomment-846755631. I haven't been able to replicate https://github.com/rust-lang/rust/pull/82653#issuecomment-849013698.

diff --cc src/bootstrap/bootstrap.py
Simple merge

diff --cc src/bootstrap/lib.rs
Simple merge

diff --cc src/bootstrap/native.rs
Simple merge