message: [terminal] Color: some older compilers do not know how to handle constexpr sqrt(). So avoid demote constexpr distance() fn to good old inline.
diff: @@ -92,7 +92,7 @@ constexpr RGBColor operator*(RGBColor c, float s) noexcept
  static_cast<uint8_t>(std::clamp(static_cast<float>(c.blue) * s, 0.0f, 255.0f)) };
  }
  -constexpr double distance(RGBColor e1, RGBColor e2) noexcept
  +inline double distance(RGBColor e1, RGBColor e2) noexcept
  {
  auto const rmean = (uint32_t(e1.red) + uint32_t(e2.red)) / 2;
  auto const r = uint32_t(e1.red) - uint32_t(e2.red);
  