Update to LLVM 5.1

[OndrejSlamecka]

Hello, I am trying to follow the tutorial but needed to do some changes to make it work with LLVM 5.1. Besides minor things:

• 825960c stopped LLVM from complaining about instructions returning void having a name.
• 816396c should fix LLVM 5.0 Error Calling Function #45 but I am not sure whether it's the right approach (e.g., why does AddrSpace stay 0?).

This is WIP. I welcome suggestions for improvement. So far I have changed only the code for chapter 3. I will change the rest of chapters' code and the tutorial text once we settle on the implementation.

[sdiehl]

So I'm attempting to keep the buildable code upstream in the llvm-hs organization. And then just keep the prose in this repo. If you want to submit the patch up there, our CI is more up to date.

[OndrejSlamecka]

Sure thing, I am leaving this PR open to make changes to the text later. For the code, I opened the following PR

llvm-hs/llvm-hs-kaleidoscope#4

[OndrejSlamecka]

Closing in favour of likely future changes to the tutorial. See
llvm-hs/llvm-hs-kaleidoscope#4