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/IceConverter.cpp b/src/IceConverter.cpp
index 9910f06..9d59c56 100644
--- a/src/IceConverter.cpp
+++ b/src/IceConverter.cpp
@@ -11,6 +11,16 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include <iostream>
+
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceClFlags.h"
@@ -23,16 +33,6 @@
 #include "IceTypes.h"
 #include "IceTypeConverter.h"
 
-#include "llvm/IR/Constant.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/Instruction.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/LLVMContext.h"
-#include "llvm/IR/Module.h"
-
-#include <iostream>
-
 using namespace llvm;
 
 namespace {