Ignore button events in the first 10 seconds after resume. On some ACPI

Ignore button events in the first 10 seconds after resume.  On some ACPI
implementations pressing the power button to wake up a machine will cause
a power button notification to happen for that button press   This would
initiate a power down, which isn't the user's intent.

Based on earlier diffs from deraadt@ and James Cook.

ok mlarkin@, "I'm not opposed" cheloha@