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/IPO/LowerBitSets.cpp b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
index db5bab0..78981fd 100644
--- a/llvm/lib/Transforms/IPO/LowerBitSets.cpp
+++ b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
@@ -1051,6 +1051,9 @@
 }
 
 bool LowerBitSets::runOnModule(Module &M) {
+  if (skipModule(M))
+    return false;
+
   bool Changed = buildBitSets();
   Changed |= eraseBitSetMetadata();
   return Changed;