Fix ScalarEvolutionExpander step scaling bug
The expandAddRecExprLiterally function incorrectly transforms
[Start + Step * X] into Step * [Start + X] instead of the correct
transform of [Step * X] + Start.
This caused https://github.com/JuliaLang/julia/issues/14704#issuecomment-174126219
due to what appeared to be sufficiently complicated loop interactions.
Patch by Jameson Nash (firstname.lastname@example.org).
Differential Revision: http://reviews.llvm.org/D16505