Remove redundant code and use C++ range fors

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@211980 91177308-0d34-0410-b5e6-96231b3b80d8
[C++11] Use more range based fors

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@211981 91177308-0d34-0410-b5e6-96231b3b80d8