Optimizing: Move optimization objects to Arena.

This should reduce the stack size needed by the
OptimizingCompiler::CompileOptimized() which was very
close to our limits for clang builds, causing repeated
build breakages on otherwise healthy changes:
    art/compiler/optimizing/optimizing_compiler.cc:395:37:
    error: stack frame size of 1760 bytes in function
    'art::OptimizingCompiler::CompileOptimized'
    [-Werror,-Wframe-larger-than=]

Change-Id: I2f4ab0235f4eac61823a4a320bb4fe78942a23c2
diff --git a/compiler/optimizing/instruction_simplifier.h b/compiler/optimizing/instruction_simplifier.h
index 0244620..668956a 100644
--- a/compiler/optimizing/instruction_simplifier.h
+++ b/compiler/optimizing/instruction_simplifier.h
@@ -36,6 +36,9 @@
   static constexpr const char* kInstructionSimplifierPassName = "instruction_simplifier";
 
   void Run() OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(InstructionSimplifier);
 };
 
 }  // namespace art