`ptr_eq` was recently enhanced to lint on more cases of raw pointers
comparison:
- lint on all raw pointer comparison, by proposing to use
`[core|std]::ptr::eq(lhs, rhs)` instead of `lhs == rhs`;
- removing one symetric `as usize` on each size if needed
- peeling any level of `as *[const|mut] _` if the remaining expression
can still be coerced into the original one (i.e., is a ref or raw
pointer to the same type as before)
The current change restricts the lint to the cases where at least one
level of symetric `as usize`, or any conversion to a raw pointer, could
be removed. For example, a direct comparaison of two raw pointers will
not trigger the lint anymore.
We do not want to remove casts done inside macros. Also, when printing
the suggestion, take it from the same context as the origin expression
(the root context).
