Atlas thunk bx elf pic detection

...d on ebx).  this delta simply identifies the "getEbx" function, identifies the base that ebx should point to generically, and sets that in workspace metadata variable "PIE_ebx".  each time a 32-bit PIE binary wants to access relative offset data, it calls this "getEbx" function, which returns 
so, i was making this change and got uncomfortable.  i feel this is the wrong answer.  because if we are not completely wrong about this working, we should get less than 100 of these (we should only get one, but i'm exaggerating for the logic discussion).  if we add this to the parent analysis module (vivisect/analysis/__init__.py) every i386 elf will end up with this vaset, whether it needs it or not.  i would rather only have the vaset created if it's actually necessary, and i'm willing to check this each time since we are only intending to see this once.  your thoughts?  i could do it either way, but i feel like this is the right way.