Make -s switch behavior consistent with Windows version

[MarioHewardt]

The -s switch needs to behave as the Windows version. On Windows, the -s switch states to only generate a dump if the condition was true throughout the -s interval. On Linux version, we generate a core dump immediately when the condition triggers and then wait for -s interval.

Here is an example of Windows:

Write up to 3 mini dumps of a process named 'consume' when it exceeds 20% CPU usage for five seconds:

C:>procdump -c 20 -s 5 -n 3 consume

So, we need to pull the metrics multiple times throughout the -s time period and only generate if they all satisfied the threshold.