Fix handling of temporaries in equivalent expression sets

[kkjeer]

The way that equality with temporary binding expressions is currently recorded can lead to false equality information. For example, in:

array_ptr<int> a;
a = _Dynamic_bounds_cast<array_ptr<const int>>(a + 1, count(1));

The second assignment will record equality between BoundsValue(TemporaryBinding(a + 1)) and a. Replacing a with its original value of a - 1 does not affect the BoundsValue expression, since the RecursiveASTVisitor class that does the replacement does not visit children of BoundsValue expressions.