Execute zero or more expressions, in order.
(exec-expr-list es compst fenv limit) → (mv vals new-compst)
The order is actually unimportant because we only call this function when either there is zero or one expression, or they are all pure.
All the expressions must return a value,
i.e. they must not be
We perform array-to-pointer conversions on all the results, because that is required by all the callers of this function.