Properly scope HLoopOptimization's allocator.

HOptimization classes do not get their destructor called,
as they are arena objects. So the scope for the optimization
allocator needs to be the Run method.

Also anticipate bisection search breakage by adding
HLoopOptimization to the list of recognized optimizations.

Change-Id: I7770989c39d5700a3b6b0a20af5d4b874dfde111
diff --git a/compiler/optimizing/loop_optimization.h b/compiler/optimizing/loop_optimization.h
index e7980ce..d12fe5e 100644
--- a/compiler/optimizing/loop_optimization.h
+++ b/compiler/optimizing/loop_optimization.h
@@ -72,7 +72,7 @@
 
   // Phase-local heap memory allocator for the loop optimizer. Storage obtained
   // through this allocator is released when the loop optimizer is done.
-  ArenaAllocator loop_allocator_;
+  ArenaAllocator* loop_allocator_;
 
   // Entries into the loop hierarchy representation.
   LoopNode* top_loop_;