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

[Rainer Orth via cfe-commits]

rorth wrote:

I don't think this is right: the test `PASS`es on Solaris/sparcv9, so this doesn't seem to be an OS issue.

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