Simplify NULL + 1 == NULL to false

[tautschnig]

This expression appears to arise in Rust's MIR when iterating over slices. See model-checking/kani#1767 for an example.

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[codecov]

Codecov Report

Base: 77.99% // Head: 77.99% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (9d51ea2) compared to base (99ce20c).
Patch coverage: 80.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7243   +/-   ##
========================================
  Coverage    77.99%   77.99%           
========================================
  Files         1619     1619           
  Lines       187184   187194   +10     
========================================
+ Hits        145999   146007    +8     
- Misses       41185    41187    +2     

Impacted Files	Coverage Δ
src/util/simplify_expr_int.cpp	85.53% <80.00%> (-0.06%)	⬇️

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[peterschrammel]

A regression test would still be great.

[tautschnig]

The CSmith test generated with random seed "1665747314" is failing for it produces too many objects. (locally) increasing the number of object bits results a verification failure, which is reproducible also with current develop. I will investigate separately.