[flang-commits] [flang] [flang] use setsid to assign the child to prevent zombie as it will be clean up by init process (PR #77944)

[Yi Wu via flang-commits]

yi-wu-arm wrote:

when forcing printout from child and parent:
```
$ ./a.out 
Parent process (PID: 273500) is running in a new session (SID: 2347).
Child process (PID: 273501) is running in a new session (SID: 273501).
```
A different session id is what we want.

https://github.com/llvm/llvm-project/pull/77944