AssetManager cookies should be int32_t and not void*.

Cookies are really indices into vectors and arrays, so
they don't need to be void*. We choose int32_t instead
of size_t to allow their width to be well specified.

(cherry picked from commit ebfdd0f467e39c3af8d92cade78263935340acb7)
(cherry picked from commit a7fa2e592e2e579e5acdb903dba83fc074ebc215)
(cherry picked from commit a9d5701b034ed2d9771b3f0943e1add00741d7cd)

Change-Id: I2aed3db568b6fdc487bf99e2c5dd123206736fda
Alarm: Add one more RTC alarm type for poweroff alarm.
Now we use type of RTC_WAKEUP for the poweroff alarm.
Actually lots of other applications also use this type.
But these applications never expect the device will
power on after it has been shut down. So we need to
add dedicated alarm type for the Deskclock or similar
applications.

Change-Id: I5df2465c46de8fe875d1581bdefe26021c8ffb33