Used std::ostringstream instead of std::stringstream wherever applicable.

src/compiler/preprocessor/new/MacroExpander.cpp

@@ -200,13 +200,13 @@ bool MacroExpander::expandMacro(const Macro& macro,
             Token& repl = replacements->front();
             if (macro.name == kLine)
             {
-                std::stringstream stream;
+                std::ostringstream stream;
                 stream << identifier.location.line;
                 repl.text = stream.str();
             }
             else if (macro.name == kFile)
             {
-                std::stringstream stream;
+                std::ostringstream stream;
                 stream << identifier.location.file;
                 repl.text = stream.str();
             }

src/compiler/preprocessor/new/Preprocessor.cpp

@@ -65,7 +65,7 @@ bool Preprocessor::init(int count,
 
 void Preprocessor::predefineMacro(const char* name, int value)
 {
-    std::stringstream stream;
+    std::ostringstream stream;
     stream << value;
 
     Token token;