Summary:
This is a redo of D45296.
It looks like the random stack-protector issues I was getting were coming from
my Android emulator, and updating everything all around and relaunching stuff
ended up making it go away.
I guess I'll have to see how it behaves on the bots.
Only additional change from the previous CL is some `const` were appropriate.
Reviewers: alekseyshl
Reviewed By: alekseyshl
Subscribers: kubamracek, delcypher, #sanitizers, llvm-commits
Differential Revision: https://reviews.llvm.org/D45461
llvm-svn: 329706