[libspnav] Add new port

[makidoll]

• What does your PR fix?

  Adds libspnav from https://github.com/FreeSpacenav/libspnav which is for SpaceMouse support. Blender uses this same library for example.

• Which triplets are supported/not supported? Have you updated the CI baseline?

  Just Linux. I was able to install through vcpkg with x64 and arm64. X11 was necessary to compile. Both VCPKG_BUILD_TYPE and VCPKG_LIBRARY_LINKAGE are respected. I haven't touched the CI baseline.

• Does your PR follow the maintainer guide?

  Yes, I think so.

[makidoll]

Thank you so much, PhoebeHui, Hoikas and NancyLi for helping! I applied your requested changes.

[makidoll]

If it's possible, can I try compiling and testing this on macOS tomorrow? (since it's 04:31 am here) I can then confirm if that works or not.

[NancyLi1013]

If it's possible, can I try compiling and testing this on macOS tomorrow? (since it's 04:31 am here) I can then confirm if that works or not.

Of course, you can do this at any time available for you. It's too late for you now. Please have a good rest first. You can update it tomorrow if it can support osx.

[makidoll]

Of course, you can do this at any time available for you. It's too late for you now. Please have a good rest first. You can update it tomorrow if it can support osx.

I looked further into this and tried to compile it, and I'm sure it would make no sense to support macOS. This library was never intended to work for Mac since you need to use a user-space driver thats only available for Linux. On top of that, there's no X11 support for Mac anymore which is required (It's XQuartz now for quite some time). The commit was from 2013. I think Blender uses the proprietary driver on Windows and Mac and libspnav on Linux.

I'm happy with the port! The only suggestion I could think of is maybe adding a comment explaining the confusion between ref v0.2.3 and libspnav-0.2.3

[NancyLi1013]

Thanks for your further investigation about this new port. It's so great.
I agree with your point that adding a comment to explain the ref.

[BillyONeal]

Thanks for your contribution!