Variable glOptionalExtensions

immutable(char[][]) glOptionalExtensions = ["GL_ARB_buffer_storage", "GL_ARB_texture_storage", "GL_ARB_texture_storage_multisample", "GL_ARB_sampler_object", "ARB_draw_elements_base_vertex", "ARB_base_instance", "ARB_viewport_array", "GL_EXT_polygon_offset_clamp"];