lwip: Fix close() might block forever if SO_LINGER=y
* Update submodule: git log --oneline ec115c720b8909364ec5898dc5cc430cc898192d..316cfc17ce24f2d5d65c9f28251ec43a59a74cb1
Detailed description of the changes:
- tcp/close: Fix clean socket closure when lignering (espressif/esp-lwip@316cfc17)
- tcp_in: Fix incomplete closure if linger active (espressif/esp-lwip@8b599aa1)
- ci: Introduce lwip test apps (espressif/esp-lwip@0866f578)
David Cermak