Update to LLVM 7.0 #52970
Description
LLVM 7.0 has been branched as of 2018-08-01, with the final tag probably a couple weeks away.
The first release candidate will be tagged in a couple of days.
Here is the llvm-dev announcement, and here is a view of the commits on the branch.
Once the final release has been tagged, Rust should be updated to LLVM 7.0.