Beginning SplitKit - utility classes for live range splitting.

This is a work in progress. So far we have some basic loop analysis to help
determine where it is useful to split a live range around a loop.

The actual loop splitting code from Splitter.cpp is also going to move in here.

llvm-svn: 108842
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index ba6be3c..4e377f9 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -68,6 +68,7 @@
   SjLjEHPrepare.cpp
   SlotIndexes.cpp
   Spiller.cpp
+  SplitKit.cpp
   Splitter.cpp
   StackProtector.cpp
   StackSlotColoring.cpp