split dom frontier handling stuff out to its own DominanceFrontier header,
so that Dominators.h is *just* domtree.  Also prune #includes a bit.

llvm-svn: 122714
diff --git a/llvm/lib/Transforms/Utils/CloneLoop.cpp b/llvm/lib/Transforms/Utils/CloneLoop.cpp
index ba8f3d5..6076ae7 100644
--- a/llvm/lib/Transforms/Utils/CloneLoop.cpp
+++ b/llvm/lib/Transforms/Utils/CloneLoop.cpp
@@ -14,7 +14,7 @@
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/BasicBlock.h"
 #include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/DominanceFrontier.h"
 
 
 using namespace llvm;