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.h b/compiler/optimizing/code_generator_x86.h
index 17787a8..033693e 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -220,7 +220,8 @@
  public:
   CodeGeneratorX86(HGraph* graph,
                    const X86InstructionSetFeatures& isa_features,
-                   const CompilerOptions& compiler_options);
+                   const CompilerOptions& compiler_options,
+                   OptimizingCompilerStats* stats = nullptr);
   virtual ~CodeGeneratorX86() {}
 
   void GenerateFrameEntry() OVERRIDE;