LLVM has recently created their 3.7 release branch, and this PR updates us to that point. This should hopefully mean that we're basically compatible with the upcoming 3.7 release. Additionally, there are a number of goodies on this branch.
* This contains a fix for https://llvm.org/bugs/show_bug.cgi?id=23957
which should help us bootstrap farther on 32-bit MSVC targets.
* There is better support for writing multiple flavors of archives, allowing us
to use the built-in LLVM support instead of the system `ar` on all current
platforms of the compiler.
* This LLVM has SafeStack support
* An [optimization patch](7cf5e26e18) by @pcwalton is included.
* A number of other minor test fixes here and there.
Due to problems dealing with the data layout we pass to LLVM, this PR also takes the time to clean up how we specific this. We no longer specify a data layout to LLVM by default and instead take the default for the target from LLVM to pass to the module that we're building. This should be more robust going into the future, and I'm also not sure we know what any of these arcane strings are any more...
d4432b3737