The non-libuv tcp server implementation had several issues:
* Relied on EINTR or self-connect through global vars for breaking,
which did not work during recv() for example.
* Never retried on EINTR
* Called recv() only once, thus subject to fragmentation issues
To support breaking otherwise blocking socket calls, RzStopPipe has been
imported from chiaki (I am the sole author so I can relicense).
rz_socket_block_time() was also detected to be doing the exact opposite
than it should on Windows through the tests, and fixed.
