cfg fix for linux

[aragonnetje6]

Describe your changes

changed cfg!(linux) to cfg!(target_os = "linux") since the former is not actually valid, but produces no bug. this wasn't causing any problem that i know of, but if the code is in here it should probably do what it says, or be removed

Issue ticket number and link

no issue created, just saw a warning when installing from master (though this warning is not showing up again for some reason)

Checklist before requesting a review

• Documentation was updated (i.e. due to changes in keybindings, commands, etc.)
• Changelog was updated with relevant user-facing changes (eg. not dependency updates,
  not performance improvements, etc.)

[ThomasFrans]

Oops, I should have read the documentation of the cfg!() macro better 😬
Nice find. I wonder why this every worked for me as I assume cfg!(linux) just doesn't do anything, but if I remember correctly the code did work on FreeBSD for example. I installed it in a VM specifically to test this code. Maybe I'm just misremembering 🤔

[hrkfdn]

Good catch indeed!