Change native paths

[hlolli]

Using non-default native paths for Overtone has resulted in the need to manually set the jna-path in the runtime for a long time. Now that tools.deps is coming to the scene, with minimal configuration at this stage. I'm planing to change the paths and use the default search paths. Instead of native/linux/x86-64 use linux-x86-64 from the root directory. This will save headaches in the long run.