cffi-libffi issue on arm (Nvidia Tegra K1)

[tjklemz]

Edit: I've narrowed the problem down to just set-gamma-ramp. I'm seeing if I can fix it to not use a cffi-libffi dependent feature of calling structures by value.

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Hi there. I have good news and bad news. The bad news is that there seems to be an issue with cffi-libffi on arm. (I'm running an Nvidia Tegra K1 with Ubuntu.) The good news is, only four one function depend on cffi-libffi. They are:

• get-video-modes
• get-video-mode
• get-gamma-ramp
• set-gamma-ramp

I have forked your repo and commented out these functions (as they don't seem to be critical): https://github.com/tjklemz/cl-glfw3/tree/remove-cffi-libffi

I then cloned that to local-projects in the quicklisp directory and re-loaded. It works great! I'm using Clozure CL.

Is there a way we can modify those four functions to not use the cffi-libffi dependency? It appears to have something to do with the :struct keyword. I'm not the best with cffi, but I may take a whack at it later tomorrow. I figured I would document the problem here, though.

[tjklemz]

Everything appears to be working after the PR. I've tested on a couple machines, including my Tegra K1. Closing this GH issue.