Subzero: Change llvm::OwningPtr to C++11's std::unique_ptr.

While I'm at it, normalize the #include order:

1. C++ library headers
2. LLVM headers
3. Subzero headers

A blank line between each group.  Each group sorted alphabetically, case-insensitive.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3930
R=jfb@chromium.org, jvoung@chromium.org

Review URL: https://codereview.chromium.org/622443002
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index b9d3170..9d9f6dc 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -15,19 +15,20 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "IceDefs.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/MathExtras.h"
+
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceClFlags.h"
+#include "IceDefs.h"
 #include "IceInstX8632.h"
 #include "IceOperand.h"
 #include "IceRegistersX8632.h"
 #include "IceTargetLoweringX8632.def"
 #include "IceTargetLoweringX8632.h"
 #include "IceUtils.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/CommandLine.h"
 
 namespace Ice {