Don;t launch on gentoo Linux

[Likhach42]

I got could not load library /home/GentUwU/.local/share/Steam/steamapps/common/Half-Life/ag/cl_dlls/client.so error

Protocol version 48 Exe version 1.1.2.2/Stdio (valve) Exe build: 20:20:44 Mar 13 2024 (10002)

[execut4ble]

Try preloading libSDL2-2.0.so.0 through launch options like described in #181

Note that OpenAG still doesn't support the 25th anniversary builds (although it's a good candidate now that the SDK is available), so consider switching to steam_legacy beta branch for best compatibility.