lwip/napt: Added necessary #include to lwip_napt.h #23

All 129 tests pass in 0s

    4 files ±0   38 suites ±0 0s ⏱️ ±0s
129 tests ±0 129 ✔️ ±0 0 💤 ±0 0 ❌ ±0
258 runs ±0 258 ✔️ ±0 0 💤 ±0 0 ❌ ±0

Results for commit 90009cc. ± Comparison against earlier commit 7896c6c.