message: GL_SILENCE_DEPRECATION was being redefined, and warning
  On macOS, GL_SILENCE_DEPRECATION is needed to remove many many warnings.
  We define it in CMakeLists.txt, but imgui_impl_opengl2.cpp defines it
  again without first checking if it's defined.  This removes that
  redefinition
diff: #define WINGDIAPI __declspec(dllimport) // Some Windows OpenGL headers need this
  #endif
  #if defined(__APPLE__)
  +#ifndef GL_SILENCE_DEPRECATION
  #define GL_SILENCE_DEPRECATION
  +#endif
  #include <OpenGL/gl.h>
  #else
  #include <GL/gl.h>
  