Also create pid file in non-daemon mode

Always make a pid file, not only when `-daemon` specified.

This is useful for troubleshooting, for attaching debuggers and loggers
and such.

- Write the pid file only after the datadir lock was acquired
- Don't create or remove a pid file on WIN32, and also don't show the option
Merge pull request #4951

d6712db Also create pid file in non-daemon mode (Wladimir J. van der Laan)