Fix a problem in TBranchElement::SetAddress in case of an object

with a level of inheritance greater than 3 and when data members are simple types
following classes at the same level (thanks Susan Kasahara for reporting
an example).
The new function has been simplified, taking advantage of the work already
done by TClass::BuildRealData.


git-svn-id: http://root.cern.ch/svn/root/trunk@5417 27541ba8-7e3a-0410-8455-c3a389f83636