Fix repeated io tests using listen sockets

The tests may fail when repeated because the listener may bind to fast
to the tcp tuple again. This is fixed by using SO_REUSEPORT instead of SO_REUSEADDR.

TIL: SO_REUSEADDR is about address wildcards and SO_REUSEPORT allows
binding to the same tcp tuple.
https://stackoverflow.com/questions/14388706/how-do-so-reuseaddr-and-so-reuseport-differ

Add a generic way to specify socket options when creating a listen socket
with tcp_listener.