[clang] [Clang-Repl] Adds custom lambda in launchExecutor and PID retrieval (PR #152562)

[Bart Chrzaszcz via cfe-commits]

bartchr808 wrote:

Ya changing that line to just 
```cpp
llvm::sys::path::append(ExecutorPath, "llvm-jitlink-executor");
```

I then get

```
Specified executor invalid: /usr/local/google/home/bartchr/.cache/bazel/_bazel_bartchr/16c24a85dd12eb0aa12cad671d68a98a/execroot/__main__/bazel-out/k8-fastbuild/bin/llvm-jitlink-executor
```

So still failing, but the expected path for bazel without the double `/bin/bin/`.

https://github.com/llvm/llvm-project/pull/152562