support shutdown animation from bootanim

- init will set sys.powerctl property and run bootanim.
- Use /oem/media/shutdownanimation.zip or
  /system/media/shutdownanimation.zip for animation file.
  If none of them exist, android animation will be used.
- Disable audio playing for shutdown animation.
- Disable TimeCheckThread for shutdown animation. It
  accesses /data partition and can block umount.

bug: 36526187
Test: many reboots

Change-Id: If02c73cda2015317d88d056cd45201208da49946
diff --git a/cmds/bootanimation/bootanim.rc b/cmds/bootanimation/bootanim.rc
index 7344ba7..469c964 100644
--- a/cmds/bootanimation/bootanim.rc
+++ b/cmds/bootanimation/bootanim.rc
@@ -1,7 +1,7 @@
 service bootanim /system/bin/bootanimation
-    class core
+    class core animation
     user graphics
     group graphics audio
     disabled
     oneshot
-    writepid /dev/stune/top-app/tasks
\ No newline at end of file
+    writepid /dev/stune/top-app/tasks