Function fill_test_data

tests/fl/gfx/blur.cpp:257–263

// ── Benchmark ────────────────────────────────────────────────────────────

static void fill_test_data(CRGB *pixels, int n) {
    for (int i = 0; i < n; ++i) {
        pixels[i] = CRGB(static_cast<uint8_t>(i * 37 + 17),
                         static_cast<uint8_t>(i * 59 + 31),
                         static_cast<uint8_t>(i * 83 + 47));
    }
}

template <typename Func>
#ifdef NDEBUG