message: Changed hopefully last remaining std::nullopt to cpp17
diff: @@ -97,7 +97,7 @@ inline cpp17::optional<TriangleToRasterize> process_prospective_tri(Vertex<float
  if (!are_vertices_ccw_in_screen_space(glm::tvec2<float>(t.v0.position),
  glm::tvec2<float>(t.v1.position),
  glm::tvec2<float>(t.v2.position)))
  - return std::nullopt;
  + return cpp17::nullopt;
  }
  // Get the bounding box of the triangle:
  @@ -110,7 +110,7 @@ inline cpp17::optional<TriangleToRasterize> process_prospective_tri(Vertex<float
  t.max_y = boundingBox.y + boundingBox.height;
  if (t.max_x <= t.min_x || t.max_y <= t.min_y) // Note: Can the width/height of the bbox be negative? Maybe we only need to check for equality here?
  - return std::nullopt;
  + return cpp17::nullopt;
  // Which of these is for texturing, mipmapping, what for perspective?
  // for partial derivatives computation
  