Work around a harmless assertion fault associated with

Work around a harmless assertion fault associated with
sqlite3VdbeMemAboutToChange() such that the detection of stale values
in registers is preserved in debugging builds, but we avoid a false-positive
assertion fault in cases involving a virtual table with a LIMIT clause
in an IN-operator loop.

FossilOrigin-Name: 9511d17e2a113dac8933663fabb0294fdc1068fd4f8224818af21266439eb7ea