Assign regions to all BBs from CodeGeneration

In order to have a valid region analysis, we assign all newly created blocks to the parent of the scop's region. This is correct for any pre-existing regions (including the scop's region and its parent), but does not discover any region inside the generated code. For Polly this is not necessary because we do not want to re-run Polly on its own generated code anyway.

Reviewers: grosser

Part of Differential Revision: http://reviews.llvm.org/D11867

llvm-svn: 244608