Revert "Temporary disable formatting error"

This reverts commit r221159, as clang-format is again back to its old behaviour
and we do not cause any buildbot error messages any more.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@221189 91177308-0d34-0410-b5e6-96231b3b80d8