Rename Reduction variables/structures to Recurrence.

A reduction is a special kind of recurrence. In the loop vectorizer we currently
identify basic reductions. Future patches will extend this to identifying basic
recurrences.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239835 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed