[llvm] [ctx_prof] Automatically convert available external linkage to local for modules with contextual roots (PR #109203)

[Mikael Holmén via llvm-commits]

mikaelholmen wrote:

If I compile with EXPENSIVE_CHECKS on a large number of lit tests fail with this patch.
E.g.
```build-all-expensive/bin/llvm-lit -av ../lld/test/wasm/lto/thin-archivecollision.ll```
fails with
```
LLVM ERROR: Function @blah changed by EliminateAvailableExternallyPass without invalidating analyses
```

https://github.com/llvm/llvm-project/pull/109203