Currently appveyor caches whole libzmq directory with all sources and
build artifacts (349MB uncompressed).
Solution: install build artifacts to separate `libzmq` directory and
cache only this (~52.70MB uncompressed).
That way we can save some space on shared cache volume that is 1GB
(compressed data) now.
* Problem: Windows build broken because of multiple issues
Windows issues:
* missing includes files
Solution: added missing <memory> and <unordered_map>
Here <map> was replaced with <unordered_map> as there is no need for
sorted map.
* googletest fails because deprecation warning causing errors.
Solution: D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING option added.
* googletest fails because by default, new Visual Studio projects
link the C runtimes dynamically but Google Test links them statically.
Solution: gtest_force_shared_crt=ON option added.
Besides that adding appveyor.yml configuration to add Windows build to
CI in order to prevent accidental Windows build breakage.
For now only Debug configuration as Release requires more time to figure
out.
* Problem: Windows build takes too long
Solution: disabling tests and perf tools
* Problem: Windows unit_tests executable not finding lizmq dll.
Solution: copy libzmq dll to build bin directory.
* Problem: Windows build fails because wrong test path provided
