Ticket #3748: add support for ksh in subshell

[d3m3t3r]

Support Korn shell variants (ksh/oksh/mksh) in the subshell.

Thank you for thinking about contributing to Midnight Commander, but we ARE NOT using pull requests to manage incoming patches!

Instead, please check out our Trac instance to see if the issue has already been reported, or submit a new ticket:

https://midnight-commander.org/wiki/NewTicket

If you chose to submit the pull request instead, keep in mind that we are not checking on them regularly, so it might take ages before we even get to it, if at all.

Unfortunately, GitHub does not allow us to disable the pull requests feature for this repository, so we have to warn you this way...

[zyv]

Closed via b683b63.