Problem: name confl from windows.h, draft API decl in pch.

Problem: zmq_poller_destroy can segfault

Problem: msvc builds are misconfigured.

Problem: test send count too high for AppVeyor CI environment

Solution:
Reduce send count so that the test does not timeout on AppVeyor CI
environment and older Windows boxes.

Solution:
- Add checks for **poller_p_ to ensure that we do not segfault when either it
  or the value within it are NULL
- Add tests for the above and increase error state coverage

Solution:
- Add error state coverage for zmq_ctx_term(), zmq_term() and
  zmq_ctx_shutdown(); zmq_ctx_destroy() is already covered since it only
  calls zmq_ctx_term()
- Add coverage for zmq_term()

Problem: scheduling parameters unused on OSX

Solution:
Mark them with LIBZMQ_UNUSED macro as per convention; although in future the
appropriate pthread code should be updated to support thread scheduling
priorities (for Mac OS X, et. al.)

tipc: add support for address domain suffix

The TIPC protocol bindings in ZeroMQ defaults to a lookup domain
of 1.0.0 to prevent 'closest first' search, and instead always
do round robin if several sockets in the network or node have
the same name published. In retrospect, this might have been a
bad idea because it won't work on standalone configurations.
We solve this by allowing an optional domain suffix to be provided
in the address, and 0.0.0 should be used in that case, or if the
TIPC address range in the cluster configuration is defined to some
other value. Domain suffixes are only relevant for connecting
addresses.
Signed-off-by: Erik Hugne <erik.hugne@gmail.com>

Problem: hint parameter throws unused warning

Fix autotools for static MinGW builds

Problem: sockfd_ parameter throws unused warning