[fpc-pascal] check if process ID is running under BSD

[Marco van de Voort]

In our previous episode, Mattias Gaertner said:
> I need to check under BSD if a PID is running and what name it has.
> Is there already a function for that?

No. Note that /proc can be turned off on BSD, and often is so on servers, so
relying on is not that safe anyway.