partitionSetParts from C to C++ interface.

Summary: partitionSetParts from C to new C++ interface.

Reviewers: grosser, Meinersbur, jdoerfert, bollu, cs15btech11044

Reviewed By: grosser, Meinersbur

Subscribers: llvm-commits, pollydev

Tags: #polly

Differential Revision: https://reviews.llvm.org/D47252

llvm-svn: 333780