Correction to allow compilation with Visual C++.

Patch contributed by Morten Ofstad. Thanks Morten!

llvm-svn: 17123
diff --git a/llvm/lib/Transforms/Scalar/LoopUnroll.cpp b/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
index 17fc35d..f87b2ca 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnroll.cpp
@@ -30,6 +30,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include <cstdio>
 #include <set>
+#include <algorithm>
+
 using namespace llvm;
 
 namespace {