Fix simple_demo on Windows

[traversaro]

🦟 Bug fix

Fixes compilation of simple_demo on Windows.

Summary

I took the missing Windows logic from wide_angle_camera example. Differently from #986, after this fix simple_demo works fine on Windows both with ogre and ogre2 plugins.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[iche033]

oh thanks for the fix, looks likes we'll need to do this for other examples in gz-rendering

[traversaro]

oh thanks for the fix, looks likes we'll need to do this for other examples in gz-rendering

I realized only later that many of this fixes were actually contained also in #291 .