tcp_rx test fails to build under debug

[lukester1975]

Hello again

> ./scripts/onload_build --kernel --user64 --have-sdci --debug
... big snip...
lib/transport/ip/tcp_rx: symbol lookup error: lib/transport/ip/tcp_rx: undefined symbol: cicp_ipif_check_ok

Presumably inlined in release or something, but I'm afraid since BROKEN_UNIT_TESTS is a thing I haven't looked at it further...

Thanks