vine: inconsistent result when wall time is exhausted

[btovar]

If a task is limited by wall time and the resource monitor is active, the task may have a result of resource exhaustion, or of max time, depending of which check happens first. If the resource monitor is not active, then it always gets max time.

We could remove the max time result, or if the resource monitor is enabled check whether the time limit was broken and change the result accordingly.

[dthain]

+1 for having both mechanisms result in the same returned error.