Solution: if inproc://zeromq.zap.01 exists, which means ZAP is
enabled, abort immediately if it cannot be used (eg: out of memory)
or it is configured incorrectly (eg: wrong socket type).
Otherwise authentication failures will simply be ignored and
unauthorised peers will be allowed to slip in.

fix bug: #2592 dish client does not resend subscriptions to radio server after radio server restart

problem: for zmq radio/dish pattern, if the radio process restarts, the dish will not resend subscriptions to radio. And the result is that the dish will never receive any more messages.

solution: in session_base_t::reconnect (), take ZMQ_DISH into consideration when invoking hiccup method.

fix bug: coredump if set linger and immediate together

In function session_base_t::reconnect, if we set immediate to 1 and set linger, we will get into first block of reconnect function, and set pipe to NULL, but we forget to cancel timer of linger. Once timer tiggered, we will get coredump. Solution: cancel timer in the end of set pipe to NULL

RELICENSE: Ilya Kulakov

Refs #2376

Suppress linker warning 4221 for MSVC

Some #define switches cause the body of entire files to be omitted. This
causes a linker warning on Visual Studio 2017, for example

    warning LNK4221: This object file does not define any previously
    undefined public symbols, so it will not be used by any link
    operation that consumes this library

Since this is warning us about something that shouldn't be
earth-shattering news, we add a linker flag to suppress this warning on
MSVC builds.

Problem: use-after-free in test_poller

Solution: remove server socket from poller before closing it
Fixes #2581

Use OBJECT_DEPENDS and OBJECT_OUTPUTS for precompiled.hpp

Problem: abort at socket creation on Android with jzmq

Solution: don't set thread name on Android

Setting a thread name on Android may fail with "permission
denied" error and abort the process due to failed assertion.
Tested on Android 5 and 6 (two phones).
Strangely enough, it only happens on signed APKs and is fine
in debug. Using JeroMQ is not an option as we need TCP keepalive
settings and authentication which JeroMQ doesn't support.

Problem: REP leaves label msgs for dead REQ in pipe

Solution: roll back the pipe if writing messages other than the
first fails in router::xsend. Roll it back also when the pipe is
terminating.
Also add test case that reproduces the memory leak when ran with
valgrind.
Fixes #2567

Revert "Problem: REP leaves label msgs for dead REQ in pipe"

Problem: REP leaves label msgs for dead REQ in pipe

Solution: roll back the pipe if writing messages other than the
first fails in router::xsend.
Also add test case that reproduces the memory leak when ran with
valgrind.
Fixes #2567

Added the license grant for jruffin

license right grant from Leonard Michelet

Relicensing grant from rotty

Problem: not using official api FD_ZERO to init fd_set

solution: fix it

In particular, on Windows, using FD_ZERO is much more efficient than
zeroing out the whole structure.

Problems: cannot use wildcard port with source address, tests bind to hardcoded TCP ports, ASAN CI run could use some improvements

Grant permission to relicense to MPL

Solution: add Ubuntu toolchain PPA and use GCC 6

Solution: pass -g so that valgrind/asan can print useful backtraces

Solution: import better solution from zproject and add a new autoconf
option

Solution: mark it as XFAIL. We tried many times to tweak the system
settings from the CI script but it still fails.

Solution: run make with -j5, as now the tests support it.

Solution: don't, libzmq's CI tests are not responsible for testing
libsodium stable releases. Save some time in the CI.

Solution: use either a wildcard IPC, or where the codepath needs to
be tested a file named after the test, so that it is unique and there
is no clash on the filesystem, allowing parallel test runs.

Solution: use ZMQ_LAST_ENDPOINT in most places. This alllows running
tests in paralle, and on over-booked shared machines where many of
the ports would be already in use.
Keep 3 tests with an hardcoded port, as there are some code paths that
require it (eg: connect before bind), but list those ports in
tests/testutil.hpp as macros so that they do not overlap and still
allow parallel runs.

These changes were inspired by a patch uploaded to Ubuntu by the
package maintainer, Steve Langasek <steve.langasek@ubuntu.com>.
Thank you Steve!