Re-enable class table for image writer

Changes, create one temporary class table per ImageInfo. Don't keep
track of class loaders.

Bug: 26317072

Change-Id: I4f9121194f39031fb8629d60b6feeb2747a77870
diff --git a/runtime/class_table.h b/runtime/class_table.h
index c911365..911f3c2 100644
--- a/runtime/class_table.h
+++ b/runtime/class_table.h
@@ -106,8 +106,7 @@
 
   // Combines all of the tables into one class set.
   size_t WriteToMemory(uint8_t* ptr) const
-      REQUIRES(Locks::classlinker_classes_lock_)
-      SHARED_REQUIRES(Locks::mutator_lock_);
+      SHARED_REQUIRES(Locks::classlinker_classes_lock_, Locks::mutator_lock_);
   size_t ReadFromMemory(uint8_t* ptr)
       REQUIRES(Locks::classlinker_classes_lock_)
       SHARED_REQUIRES(Locks::mutator_lock_);