[stage 2 projects] Enable new points-to solver

[Daniel Berlin]

> - Pointer arithmetic used to confuse the new solver.  If it saw
>   PTR + OFFSET, it would create one ANYTHING constraint for
>   OFFSET, which would then be transferred into the pointer as
>   "points-to anything" attribute.

BTW, we can actually do better than this if we know that the offset is
going to land on a field, and the user isn't just marching through the
structure byte by byte.  Then we can safely use a regular deref + offset
constraint, and get much better results.