Handle undefined results properly

[lkorenc]

Currently some instruction may leave an output value undefined, e.g. ROR. Ideally, circuit should accept both (we consider OF to be undefined after ->) t1: [ ... ] -> t2: [ OF = 0 ] t1: [ ... ] -> t2: [ OF = 1 ]

• [x] remill semantics needs to be modified. Currently undefined result are also undefined in a semantics (sometimes undefined intrinsic is used, sometimes they are left as they were or arbitrary value is used). To handle this properly semantics must be uniformed - ideally by using __remill_undefined.

In circuitous we have several ways of handling this:

• [x] Assume tracer will preserve undefined values and adjust
• [ ] Add define bit into trace, that says if value if defined (undefined value cannot be read) - does not require tracer modification but can be done in circuitous interpreter instead.

[lkorenc]

See https://github.com/lifting-bits/remill/issues/541 for information about particular semantics and to report newly found inconsistent instructions.