ENH: Fix issue with parallel execution of the same do-file on Unix systems.

[tobiasraabe]

Is your feature request related to a problem?

Stata produces log files which have the same name as the executed do-file when used in batch mode.

Parallelizing over the same do-file ...

1. may create multiple workers which want to create the same log file at the same time.
2. may overwrite the log produced by one task with the information from another task. Whether a task fails is partly inferred from the log file,

On Windows, there is a hacky and maybe not even intended work-around to rename the log file for every task which does not work on Unix.

Describe the solution you'd like

Nothing discussed so far.

[tobiasraabe]

Use output redirection on Unix: https://stackoverflow.com/a/6482200.