timerfd: Add alarm timers
timerfd: Add alarm timers

Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
thereby enabling wakeup alarm timers via file descriptors.

Signed-off-by: Todd Poynor <57cb0497077c01018e8c022963d2feeac2e977b4@google.com>
Signed-off-by: John Stultz <33837adfb53316eae44aad04041e1240088d76fd@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs