Solution: Use wepoll on Windows

Solution: import wepoll 1.5.0 source

Problem: test_inproc_connect not using test framework

Improve socket inheritance handling

Solution: migrate to unity

Solution: create sockets with WSA_FLAG_NO_HANDLE_INHERIT

Solution: extracted make_socket_noninheritable function

Solution: make error handling consistent and use retired_fd to remove code duplication

Allow EBADF on iOS #3046

Migrated some more tests to unity and fixed some more code style issues

Split poller config and disable 'poll' poller on Windows for I/O thread polling

Solution: add const

Solution: removed

Solution: add alloc_assert

Solution: use API_POLLER=poll instead of POLLER=poll

Problem: API poller cannot be set independently from I/O thread poller, poll I/O thread poller broken on Windows

Solution: change platform definitions to separate API poller from I/O thread poller, disallow configuring poll I/O thread poller on Windows

Solution: migrate to unity

Solution: insert some sleeps to remedy timing dependencies

Solution: migrate to unity

Solution: migrate to unity

Solution: added test case, reproduces the likely cause for #3107

* Update zmq_connect documentation to mention issue of multiple connects to the same endpoint

Fix some more code style issues

Solution: replace by C++-style casts

Solution: add no-return attributes

Solution: add alloc_assert calls

Solution: replace by for loop

Solution: restructured code, inverted condition

Solution: properly declared underlying type of enum declaring retired_fd

Solution: fix #if/#else structure

Solution: change options_t.type to int8_t

Fix some code style issues

Solution: remove redundant else

Solution: reduce to newly extracted function clear, which does not use the freed pointer

Solution: add code to make non-use explicit

Solution: call check_read instead

Solution: add explicit

Fixed compilation with ZMQ_ATOMIC_PTR_MUTEX