Add OptimizingCompilerStats to the CodeGenerator class.

Just refactoring, not yet used, but will be used by the incoming patch
series and future CodeGen specific stats.

Change-Id: I7d20489907b82678120518a77bdab9c4cc58f937
Signed-off-by: Serban Constantinescu <serban.constantinescu@linaro.org>
diff --git a/compiler/optimizing/code_generator_x86_64.h b/compiler/optimizing/code_generator_x86_64.h
index 21357be..8ee0a7a 100644
--- a/compiler/optimizing/code_generator_x86_64.h
+++ b/compiler/optimizing/code_generator_x86_64.h
@@ -220,7 +220,8 @@
  public:
   CodeGeneratorX86_64(HGraph* graph,
                   const X86_64InstructionSetFeatures& isa_features,
-                  const CompilerOptions& compiler_options);
+                  const CompilerOptions& compiler_options,
+                  OptimizingCompilerStats* stats = nullptr);
   virtual ~CodeGeneratorX86_64() {}
 
   void GenerateFrameEntry() OVERRIDE;