In TStreamerInfo::BuildOLd, always force data members of a fake class to be aligned

on a 4 bytes boundary (32 bits machines) or 8 bytes on 64 bits machines.
With this fix, DrawTest.sh works correctly on alpha.


git-svn-id: http://root.cern.ch/svn/root/trunk@3786 27541ba8-7e3a-0410-8455-c3a389f83636