Oops - LiveIntervalUnion.cpp file does use std::find. Moving STL header include to LiveIntervalUnion.cpp file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147089 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalUnion.cpp b/lib/CodeGen/LiveIntervalUnion.cpp
index 110fe1e..60a6880 100644
--- a/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/lib/CodeGen/LiveIntervalUnion.cpp
@@ -21,6 +21,8 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 
+#include <algorithm>
+
 using namespace llvm;