Remove unnecessary lval domain special cases

[sim642]

Closes #998. This fixes the crash on Concrat's brubeck benchmark.

Since address domain keeps them in different buckets anyway, these special cases are no longer needed. By removing them, the the issue of bucket keys conflicting due to these overrides is fixed. The identity of offsets is thus completely standard and can be derived.

This requires a small fix in the evaluation of pointer equalities, which previously used VD.equal. VD.equal is not appropriate for semantic equality and is replaced with actual evaluation. A check in 21-casts/01-via_ptr, which checked VD.equal {f[def_exc:0]} {f[def_exc:0].x}, broke because the elements are no longer equal due to the offset equality handling such special case.

EDIT: sv-benchmarks runs show no difference in results or performance.