Revert "Added support for modulo expressions"

This reverts commit 215684. The intention of the commit is great, but
unfortunately it seems to be the cause of 14 LNT test suite failures:

http://lab.llvm.org:8011/builders/perf-x86_64-penryn-O3-polly/builds/116

To make our buildbots and performance testers green until this issue is solved,
we temporarily revert this commit.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@215816 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "[Refactor] Cleanup runtime code generation"

This reverts commit 215466 (and 215528, a trivial formatting fix).

The intention of these commits is a good one, but unfortunately they broke
our LNT buildbot:

http://lab.llvm.org:8011/builders/perf-x86_64-penryn-O3-polly-codegen-isl

Several of the cleanup changes that have been combined in this 'fixup' are
trivial and could probably be committed as obvious changes without risking to
break the build. The remaining changes are little and it should be easy to
figure out what went wrong.

git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@215817 91177308-0d34-0410-b5e6-96231b3b80d8