Your system information

• Steam client version (build number or date): Steam package version 1490228413 built on Mar 22 2017 at 23:45:04
• Distribution (e.g. Ubuntu): Xubuntu 16.04 64-bit
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen.

What I expected: Steam won't do anything with games that aren't installed or aren't available

What did happened: Steam downloads workshop content for a non-Linux game on Linux.

Steps for reproducing this issue:

1. Have Steam for Linux and a non-Linux game.
2. Be subscribed to workshop content for that game.
3. When that content updates, Steam downloads the updates but there's no point at all since the game isn't installable anyway.

Image showing this issue: http://i.imgur.com/2zg6ptr.png