selftests/timers: Add leapcrash test from the timetest suite

selftests/timers: Add leapcrash test from the timetest suite

This change adds the leapcrash test which tests to see if a
leapsecond deadlock which was observed from 2.6.26 to 3.3
is present on this system.

Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>