rust/src/libcompiler_builtins
bors 0777c757a6 Auto merge of #40123 - TimNN:llvm40, r=alexcrichton
LLVM 4.0 Upgrade

Since nobody has done this yet, I decided to get things started:

**Todo:**

* [x] push the relevant commits to `rust-lang/llvm` and `rust-lang/compiler-rt`
* [x] cleanup `.gitmodules`
* [x] Verify if there are any other commits from `rust-lang/llvm` which need backporting
* [x] Investigate / fix debuginfo ("`<optimized out>`") failures
* [x] Use correct emscripten version in docker image

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Closes #37609.

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**Test results:**

Everything is green 🎉
2017-04-24 22:18:16 +00:00
..