we don't detect LLVM needing a rebuild correctly in `llvm-finished-building`

```
% ./build/x86_64-unknown-linux-gnu/stage1/bin/rustc  -Clto ../src/test/ui/issues/issue-44056.rs
Segmentation fault (core dumped)
```

fortunately:

```
% ./build/x86_64-unknown-linux-gnu/stage1/bin/rustc ../src/test/ui/issues/issue-44056.rs
% 
```

 cc #44056 