Re-commit optimization bisect support (r267022) without new pass manager support.

The original commit was reverted because of a buildbot problem with LazyCallGraph::SCC handling (not related to the OptBisect handling).

Differential Revision: http://reviews.llvm.org/D19172

llvm-svn: 267231
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 01a8ad8..685ce9e 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -787,7 +787,7 @@
   Optional<bool> ProvidedRuntime;
 
   bool runOnLoop(Loop *L, LPPassManager &) override {
-    if (skipOptnoneFunction(L))
+    if (skipLoop(L))
       return false;
 
     Function &F = *L->getHeader()->getParent();