Update systray_linux.c

[cocotyty]

support set title on linux.

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• [*] Do the tests pass? Consistently?
• Did this change improve test coverage?
• Has it been reviewed/approved by relevant teammates?
• Can it be QA’d in staging or something like staging?
• Is the code in question being linted? If not, consider adding a linter step to CI. If yes, make sure the linter is happy.
• Do we know how we’re going to deploy this?
• Are we clear on what the support and maintenance impact is?
• Did you create new documentation? Is it accessible and in the right place?
• Has existing documentation been updated?
• Have you logged tickets for related technical debt with the label “techdebt”?

[Crosse]

Thanks! I've fixed some whitespace issues and will merge in a minute.