Fix the `w4-any` solver so that it waits for the first non-error result before returning.  If all solvers return error results, the collection of all errors is returned and presented to the user.
Fix the `w4-any` solver so that it waits for the first non-error
result before returning.  If all solvers return error results,
the collection of all errors is returned and presented to the user.

GaloisInc/cryptol,GaloisInc/cryptol,GaloisInc/cryptol