lwip: enable LWIP_SO_RCVTIMEO if sock layer is used

[benpicco]

Contribution description

It is extremely counter-intuitive that LWIP will by default ignore timeouts unless LWIP_SO_RCVTIMEO is set.
When using the sock API, the application should not have to care what backend is used and timeouts are part of the sock API - so always enable timeouts in LWIP when the sock API is in use.

Testing procedure

lwip tests should still pass without manually setting LWIP_SO_RCVTIMEO

tests/lwip_sock_udp

main(): This is RIOT! (Version: 2022.04-devel-779-gca8c8-LWIP_SO_RCVTIMEO)
code 0x41
Calling test_sock_udp_create6__EADDRINUSE()
Calling test_sock_udp_create6__EAFNOSUPPORT()
Calling test_sock_udp_create6__EINVAL_addr()
Calling test_sock_udp_create6__EINVAL_netif()
Calling test_sock_udp_create6__no_endpoints()
Calling test_sock_udp_create6__only_local()
Calling test_sock_udp_create6__only_local_port0()
Calling test_sock_udp_create6__only_local_reuse_ep()
Calling test_sock_udp_create6__only_remote()
Calling test_sock_udp_create6__full()
Calling test_sock_udp_recv6__EADDRNOTAVAIL()
Calling test_sock_udp_recv6__EAGAIN()
Calling test_sock_udp_recv6__ENOBUFS()
Calling test_sock_udp_recv6__ETIMEDOUT()
 * Calling sock_udp_recv()
 * (timed out with timeout 1000000)
Calling test_sock_udp_recv6__socketed()
Calling test_sock_udp_recv6__socketed_with_remote()
Calling test_sock_udp_recv6__socketed_with_port0()
Calling test_sock_udp_recv6__unsocketed()
Calling test_sock_udp_recv6__unsocketed_with_remote()
Calling test_sock_udp_recv6__with_timeout()
Calling test_sock_udp_recv6__non_blocking()
Calling test_sock_udp_recv6__aux()
Calling test_sock_udp_recv_buf6__success()
Calling test_sock_udp_send6__EAFNOSUPPORT()
Calling test_sock_udp_send6__EINVAL_addr()
Calling test_sock_udp_send6__EINVAL_netif()
Calling test_sock_udp_send6__EINVAL_port()
Calling test_sock_udp_send6__EHOSTUNREACH()
Calling test_sock_udp_send6__ENOTCONN()
Calling test_sock_udp_send6__socketed_no_local_no_netif()
Calling test_sock_udp_send6__socketed_no_netif()
Calling test_sock_udp_send6__socketed_no_local()
Calling test_sock_udp_send6__socketed()
Calling test_sock_udp_sendv6__socketed()
Calling test_sock_udp_send6__socketed_other_remote()
Calling test_sock_udp_send6__unsocketed_no_local_no_netif()
Calling test_sock_udp_send6__unsocketed_no_netif()
Calling test_sock_udp_send6__unsocketed_no_local()
Calling test_sock_udp_send6__unsocketed()
Calling test_sock_udp_send6__no_sock_no_netif()
Calling test_sock_udp_send6__no_sock()
ALL TESTS SUCCESSFUL

Issues/PRs references

[kfessel]

Did you check weather lwip sock_* depends on any timer (on the first glance it did not) - on the second sock_* -> lwip_sock_* -> lwip_* -> lwip_contrib -> ztimer_msec

[benpicco]

lwip will pull in ztimer_msec through lwip_contrib.

[miri64]

Would preferred this switch to be in pkg/lwip/include/lwipopts.h. Could this maybe be done as a follow-up?