[Polly] Translate Scop::DomainMap to islpp

Reviewers: grosser, Meinersbur, bollu

Subscribers: pollydev

Tags: #polly

Contributed-by: Nandini Singhal <cs15mtech01004@iith.ac.in>

Differential Revision: https://reviews.llvm.org/D35453

llvm-svn: 308093