Jansi-native libraries are not stack protected

[hs-martinbg]

The checksec tool (http://www.trapkit.de/tools/checksec.html) reports that the native libraries are not stack protected. The lack of the protection could lead to change of control flow by overwriting the return address from a function on the stack.

The result of the tool execution was that no canary was found in both linux libraries:

[gnodet]

I'm planning a release soon, so if you can provide any hint on how to fix the problem, I'll happily have a look.