Refinements to array and class object size computation.

* Rename dvmArrayObjectLength to dvmArrayObjectSize.  In the context
  of arrays length may refer to the length of the array data and not
  the size of the array object instance.

* Add a new method dvmClassObjectSize which computes the total size of
  a class object including its static fields.

Change-Id: I693ec8e66dfa5df35c9f35474c80411ea917c899