Set up StatsCompanionService.java

Introduces StatsCompanionService.java and sets it up as a system service.

This service is a helper for statsd. It will be responsible for setting
and cancelling alarms related to polling stats and anomaly detection.

It currently does not have selinux permission, so must be started
manually (or with selinux temporarily disabled).

Test: disable enforcing selinux, then set and cancel alarms and make
sure they work.

Change-Id: I3bd73acdd998ee424696cce40965134c14220d8f
diff --git a/Android.mk b/Android.mk
index 76ca9b9..8e09267 100644
--- a/Android.mk
+++ b/Android.mk
@@ -270,6 +270,7 @@
 	core/java/android/os/IRecoverySystemProgressListener.aidl \
 	core/java/android/os/IRemoteCallback.aidl \
 	core/java/android/os/ISchedulingPolicyService.aidl \
+	core/java/android/os/IStatsCompanionService.aidl \
 	core/java/android/os/IStatsManager.aidl \
 	core/java/android/os/IThermalEventListener.aidl \
 	core/java/android/os/IThermalService.aidl \