neat bug in alias analysis

[Mark Mitchell]

Actually, I don't buy the point about pointers-to-const after all.
When we're looking for an alias set, we're looking for the thing
pointed to.  So, the alias set for `const int *' should not be the
same as the alias set for `int *'; these are not compatible types,
even in C.  

  const int **p1;
  int **p2;
  
We know that `*p1' cannot change `*p2'.  

So, I stand by my original proposal.  For the moment.

--
Mark Mitchell                   mark@codesourcery.com
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