[WebAssembly] Import wasm_simd128.h from Emscripten

Authored by tlively on Mar 27 2020, 4:34 PM.


[WebAssembly] Import wasm_simd128.h from Emscripten

As the WebAssembly SIMD proposal nears stabilization, there is desire
to use it with toolchains other than Emscripten. Moving the intrinsics
header to clang will make it available to WASI toolchains as well.

Reviewers: aheejin, sunfish

Subscribers: dschuff, mgorny, sbc100, jgravelle-google, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76959