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/IceTypeConverter.cpp b/src/IceTypeConverter.cpp
index 078c664b..6e8138f 100644
--- a/src/IceTypeConverter.cpp
+++ b/src/IceTypeConverter.cpp
@@ -12,9 +12,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "IceTypeConverter.h"
 #include "llvm/Support/raw_ostream.h"
 
+#include "IceTypeConverter.h"
+
 namespace Ice {
 
 TypeConverter::TypeConverter(llvm::LLVMContext &Context) {