Disable and remove finger.

Finger is useless for multithreaded GC, removing it should provide a
slight speed up due to avoided comparison.

Change-Id: I7eb7abcbab8d3307807b1086c06d68b2d4bcd2e9
diff --git a/runtime/gc/accounting/heap_bitmap-inl.h b/runtime/gc/accounting/heap_bitmap-inl.h
index f6cf2b5..0524ccb 100644
--- a/runtime/gc/accounting/heap_bitmap-inl.h
+++ b/runtime/gc/accounting/heap_bitmap-inl.h
@@ -30,7 +30,7 @@
   for (It it = continuous_space_bitmaps_.begin(), end = continuous_space_bitmaps_.end();
       it != end; ++it) {
     SpaceBitmap* bitmap = *it;
-    bitmap->VisitMarkedRange(bitmap->HeapBegin(), bitmap->HeapLimit(), visitor, VoidFunctor());
+    bitmap->VisitMarkedRange(bitmap->HeapBegin(), bitmap->HeapLimit(), visitor);
   }
   // TODO: C++0x auto
   typedef SpaceSetMapVector::iterator It2;