"gluErrorString" is deprecated

[Libero0809]

Hi Cem,

I am using Visual Studio 22, OpenGL 3.3, GLFW, and GLAD on windows.
When I use cyGL.h, I get a compile error of "error C3861: 'gluErrorString': identifier not found". It seems that 'gluErrorString' is deprecated in some modern OpenGL.

I currently solve it by adding the 'gluErrorString' function on this page to my code: https://github.com/libigl/libigl/blob/main/include/igl/opengl/report_gl_error.cpp

Is it possible to use other methods, such as compile definitions, to fix that?

[LEGOL2]

Fixed in #36