Fix valgrind errors.

For now just stack allocate the code generator. Will think
about cleaning up the root problem later (CodeGenerator being an
arena object).

Change-Id: I161a6f61c5f27ea88851b446f3c1e12ee9c594d7
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 610625c..660294b 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -124,7 +124,7 @@
 class CodeGeneratorARM : public CodeGenerator {
  public:
   explicit CodeGeneratorARM(HGraph* graph);
-  virtual ~CodeGeneratorARM() { }
+  virtual ~CodeGeneratorARM() {}
 
   virtual void GenerateFrameEntry() OVERRIDE;
   virtual void GenerateFrameExit() OVERRIDE;