Problem: build fails due to undefined INT_MAX

Solution: remove debug printf line completely

Solution: include stdint.h

Solution: include climits

Fixes #1720

truncate rc to INT_MAX for send/recv

to avoid overflow for large messages

send/recv still succeed for large messages,
but `zmq_msg_size` must be used to get the true size.

Last bits of Hurd support

Problem: typo

Solution: fix it

Problem: client over inproc receives the msg with routing id set

Problem: configure --without-documentation is clumsy

It's inconsistent, and should be --with-something=yes/no. Also the
term 'documentation' is long and clumy.

Solution: use --with-docs instead.

problem: condition variable setting invalid timeout

restore check for MSC 1600 before including stdint.h

GNU/Hurd support

include tweetnacl in dists

Problem: OpenWRT Makefile still uses tarballs, now using GIT HEAD master

Problem: no support for OpenWRT

Specifically, the RedHat tools.

Solution: move this into packaging/

Solution: copy ZeroMQ packaging script from
https://github.com/vperron/openwrt-zmq-packages

Note: this is not usable as-such, needs fixing.

Add support for the RelWithDebInfo CMake configuration.

It's now possible to build Release version with pdb file.

Problem: On Windows CI, in tests/test_timers.c, "Windows.hpp" could not be found.

found.
Solution: Include the source directory

Problem: _sleep is a library function of Windows.
Solution: use sleep_

Problem: Windows CI fails due to libsodium build failure

Solution: Use stable branch of libsodium

problem: when socket is destroyed before zmq_poller is the zmq_poller is accessing a dead socket

Problem: Android build is too slow

Solution: use parallel make (-j 4) and don't build man pages.

Test for issue #1690 (ZMQ_REQ_RELAXED)

Current ZMQ_REQ_RELAXED test improvement to check that pipes are not closed
after executing two send() in a row with no recv() in between.

Fixed issue #1690 (ZMQ_REQ_RELAXED)