LiveIntervalUnion is not used in RegAllocBase.

Patch by Matthias Braun!

llvm-svn: 188389
diff --git a/llvm/lib/CodeGen/RegAllocBase.h b/llvm/lib/CodeGen/RegAllocBase.h
index ccaabba..84cf3a2 100644
--- a/llvm/lib/CodeGen/RegAllocBase.h
+++ b/llvm/lib/CodeGen/RegAllocBase.h
@@ -38,7 +38,7 @@
 #define LLVM_CODEGEN_REGALLOCBASE
 
 #include "llvm/ADT/OwningPtr.h"
-#include "llvm/CodeGen/LiveIntervalUnion.h"
+#include "llvm/CodeGen/LiveInterval.h"
 #include "llvm/CodeGen/RegisterClassInfo.h"
 
 namespace llvm {