Poll() implementation for Windows Vista+

Solution: Provide poll() for Windows as well. This is a build option that
defaults to off as the resulting binary will only run on Windows Vista or
newer.

This is not tested with alternative Winsock service providers like VMCI,
but the documentation for WSAPoll does not mention limitations.

On my local machine, throughput improves by ~10 % (20 simultaneous
remote_thr workes to one local_thr, 10 byte messages), while latency
improves by ~30 % (measured with remote/local_lat).

Solution: Always use fd_t when accessing the pollset.

Problem: std:vector.data breaks compat with C++98

Solution: use buffer address instead

Fix build error in MSVC11

(and probably other MSVC versions)

Problem: Android CI NDK version and C++ ABI are outdated

Solution: switch to 4.9

Solution: update CI scripts to use newer r11c from r10e

Solution: use a variable for easier maintenance, in sync with zproject

allow to build sparc (v8,leon)

Only set sparcv9 optimization for sparc64 systems.
This allows to run for example application using zeromq
on sparc32 systems.
Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>

Problem: update zmq_setsockopt doc with new flag name

Fix compilation with mingw64 using autotools

VMCI family does not support non-blocking sockets.

It may even cause BSOD on Windows.

Windows Subsystem for Linux compatibility fix

On systems where getifaddrs() exists but isn't implemented, behave as if 'resolve_nic_name()' were entirely unsupported

Problem: msvc imports missing Rule.Category declarations.

Problem: style broken in src/windows.hpp

Solution:
Wrap to lte 80 chars and fix it.

Problem: no unit tests for base85 or public curve functions.

Problem: no function to derive public key from curve secret.

Problem: unresolved dgram externals in msvc builds.

Typo in define for libsodium

Since ZMQ_USE_SODIUM is nowhere defined i guess it's meant to be ZMQ_USE_LIBSODIUM?

Problem: Wrapping issue in test for SRCFD [style]

Solution:
Wrap it.

Problem: my name is not in the AUTHORS file

problem: no way to send raw udp messages with zeromq