Compilation fails on FreeBSD because not all POSIX
compliant systems end up including AF_INET from
other header files transitively.

AF_INET and AF_INET6 should be provided by
<sys/socket.h>.

Fix bins/opt/end2end_test --gtest_filter=ProxyEnd2end/ProxyEnd2endTest.RpcDeadlineExpires/1 GRPC_POLL_STRATEGY=poll

Since

    #...
    class Service:

    class NextService:
    #...

without a body or `pass` under `Service` is invalid
Python, we ensure a `pass` statement is always
emitted to make the generated code valid.

In all cases when writing, respect what the peer has asked for (not what the peer has acknowledged we asked for)