fix _GNU_SOURCE redefined warning

[cornelk]

Closes #351

In upstream the _GNU_SOURCE and poll changes introduced this:

glfw/glfw@9f73e9a
glfw/glfw@adc202d

[Jacalz]

You might want to contribute this change upstream. I'm not sure modifying the Glfw source in this way is the best option. It will be removed as soon as Glfw is updated again.

[cornelk]

@Jacalz this has already been fixed in upstream (i guess for 3.4): glfw/glfw@bb9d699 - I am not sure what to do here

[Jacalz]

I think it would be best to get a PR up to fix the issue for their next 3.3.x release. Otherwise it's just going to be undone work when we update to the next release in that series.

That would mean targeting the 3.3-stable branch: https://github.com/glfw/glfw/tree/3.3-stable.

[cornelk]

@Jacalz I have a feeling that this will not get accepted ( glfw/glfw#2133 (comment) ) but I will submit it there

[dmitshur]

@cornelk I think what I wrote in #351 (comment) applies. If the problem can be reproduced with the GLFW C source code (independently of the Go bindings), then it's reasonable to target the fix there. The report in glfw/glfw#2133 refers to the Go bindings, which is suboptimal for that issue tracker. We should investigate that on our side in #351.

[cornelk]

@Jacalz i believe i have found the proper fix now by changing the import order, i see no warning anymore (i am on Linux) using:

cd v3.3/glfw/
go clean -cache
go build ./...

@dmitshur thanks for the tip, i checked and could build glfw 3.3 stable without any warning.

[Jacalz]

Cool. Nice work 👍

[Jacalz]

Nice work. Thanks for the fix.

[dmitshur]

Thanks.