Implementing num_secs_to_wakeup support

[Gabriel Burt]

Hi,

The Suspend and SuspendHybrid take an int arg num_secs_to_wakeup, but
it looks like the linux implementation raises the AlarmNotSupported
exception if you pass anything but 0, and the freebsd implementation
simply ignores it.

Would the best way to fix this be to modify pm-utils/functions to look
for an environment variable, say $PM_NUM_SECS_TO_WAKEUP, and use
rtcwake to do the suspend/hibernate/etc if it's set?

Thanks!

Gabriel