Add #includes that were eliminated from headers


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4380 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAlloc/InterferenceGraph.cpp b/lib/CodeGen/RegAlloc/InterferenceGraph.cpp
index 9e73721..d18fdda 100644
--- a/lib/CodeGen/RegAlloc/InterferenceGraph.cpp
+++ b/lib/CodeGen/RegAlloc/InterferenceGraph.cpp
@@ -5,6 +5,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/InterferenceGraph.h"
+#include "llvm/CodeGen/IGNode.h"
 #include "llvm/CodeGen/RegAllocCommon.h"
 #include "Support/STLExtras.h"
 #include <algorithm>