Wasm simd support

[cuberoot]

I tried to run the Hako using WasmKit, but I got the following error:

Message(text: "Illegal opcode: [253]")" at offset 0xfd

I looked up the opcode and it's related to simd support. Are there any plans to support simd?

[kateinoigakukun]

Yes, I have a plan to add SIMD support, stay tuned.

[andrewmd5]

I’m working on the Swift host implementation for Hako and ended up writing software SIMD in my WasmKit fork; if it’s meaningful I can open a PR.

[kateinoigakukun]

Thanks @andrewmd5, feel free to open PR :)