Test dumping instead of SCHEDULER_STOPPED() since the latter isn'ttrue when doadump is called from ddb.

[imp]

Summary

When doing a dump, the scheduler is normally not running, so this
changed worked to capture dumps for me. However, the test for
SCHEDULER_STOPPED() isn't right. We can also call the dump routine
from ddb, in which case the scheduler is still running. This leads to
an assertion panic that we're sleeping when we shouldn't. Instead, use
the proper test for dumping or not. This brings us in line with other
places that do special things while we're doing polled I/O like this.

Noticed by: pho@
Sponsored by: Netflix

[imp]

sys/cam/cam_periph.c

1214 ↗

(On Diff #36711)

yea, I know it's a little churn here, but it's the only place we have negative logic so I thought it was clearer to switch.

[markj]

Peter, would you be able to try this patch with the scenario you were testing before?

[markj]

Looks ok to me.

[pho]

In D13531#282857, @markj wrote:

Peter, would you be able to try this patch with the scenario you were testing before?

Sure. This works for me.

[kmacy]

This seems to fix dumps from panics caused by in-kernel page faults.