This patch  adds a new member of type deque to the
xpub class that contains pointers to metadata_t.
This deque is then used (alongside pending_data
and pending_flags) to preserve metadata when
copying messages.

CI run on OSX needs binutils

problem: trying to support polling on thread safe sockets with zmq_poll failed

OSX does not ship with binutils, need to install it before the script
run via brew in order to be able to use greadelf, needed by the
qt-android CI script.

problem: new poller field in zmq_pollitem_t is changing the api

Problem: tests fail after PR #1531

apply a change to LIBZMQ_DELETE macro (related to issue #1524)

define a macro for heap object deletion in a unified manner (related …

Container-based CI build

CI build does not fail when tests fail. Fix #1527

problem: new field is breaking existing code

problem: user cannot poll on thread safe sockets

fixed issue with ticket #1517 (wrong lib output name in MSVC CMake bu…

fixed issue with ticket #1517 (wrong lib output name in MSVC CMake build) and apply some improvements in CMake build system

changing some camelCase variable names to snake_case in previous commit

remove unnecessary multiple WSAGetLastError() calls

place a ZMQ_UNUSED macro and replace all unused variables with ZMQ_UNUSED macro

Problem: Missing src/ prefix for libzmq library in Makefile.am ...

Solution: Add prefix to fix test compilation

Problem: lack test case for large stream messages

Merge fix for zeromq/zeromq4-1#52, getsockopt ZMQ_RCVMORE now resets all bits