cmake: Use LOCATION property only for imported targets

Newer CMake versions allow use of the LOCATION target property only for
imported targets (CMP0026). Because the old package variables are only
needed for backward compatibility after configuration they could be
deactivated for super projects which build ZeroMQ together with other
projects.
Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

cmake: Remove build/msvc include path to remove file name clash

Remove the `build/msvc` include path from the test project to fix a
problem with the order of the include paths. Additionally remove the
unnecessary `include_directories` from the master project.
Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

CMake: Add cross compiling support and export targets to package config

appveyor: Use correct CURVE security options

The AppVeyor build test options mismatch between command line options
and CMake CURVE security options. Rename the command line options to
the correct names.
Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

RELICENSE: mauri-melato grant

Update the mauri-melato libzmq fork

Relicense

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>

RELICENSE: Jake Cobb grant

RELICENSE : Bruno Bodin grant

Unnecessary dynamic memory allocation in zmq_poller_poll()

Unnecessary dynamic memory allocation for zmq::socket_poller_t in zmq_poller_poll(). Fixed by allocating zmq::socket_poller_t from stack.

* Prevent DOS by asserts in TCP tuning

-Propagates socket option errors from the
tuning functions to the callers.
-Asserts a subset of error conditions during tuning,
excluding external network causes.
-Checks tuning results in 3 call sites and treats
them like failures to connect, accept, etc.

* Fix variable name

* Remove lambda requiring C++11

* add define for windows/UWP

* prevent issue with COM references

* gettickcount not available on uwp

* add compiler definitions

* add convenitnece cmake file

* brute force uwp compilation

* fix compiler version

* cosmetics

Relicense: Wouter Overmeire (lodagro)

RELICENSE: Juha Reunanen / Tomaattinen / Outotec grant

Problem: msg_t leaks/unhandled failures (and bad style).

License grant