Prefer ANDROID_ALARM_ELAPSED_REALTIME over CLOCK_MONOTONIC

The CLOCK_MONOTONIC might get frozen during suspend. The android
specific ANDROID_ALARM_ELAPSED_REALTIME does not have this problem
and should be used when possible.

[iphb] Prefer ANDROID_ALARM_ELAPSED_REALTIME over CLOCK_MONOTONIC
Merge pull request #29 from spiiroin/monotonic_time

Prefer ANDROID_ALARM_ELAPSED_REALTIME over CLOCK_MONOTONIC