Upgrade LLVM JIT

[revmischa]

For new LLVM version (9+)
Doesn't quite work. Need help.

[labkey-matthewb]

Hi Mischa, I made a similar change a few weeks ago when I upgrade a machine to Ubuntu 20.04. In addition to these few changes, I had to change the build to use c++14. That is why I didn't immediately create a PR, because I don't really know the implications of that.

See this commit on branch llvm_10:

58e0a51

[revmischa]

When I ran it with my changes I get bad access crash when it initializes the engine
ExecutionEngine* executionEngine = EngineBuilder(std::move(jitx.module_ptr)).create();

[labkey-matthewb]

When I ran it with my changes I get bad access crash when it initializes the engine
ExecutionEngine* executionEngine = EngineBuilder(std::move(jitx.module_ptr)).create();

Maybe some subtle difference between llvm::make_unique/move and std::make_unique/move? (I haven't looked inside the implementation)

[revmischa]

Done in #470 and kblaschke@0dc7efe