Label /dev/rtc0 as rtc_device.

Grant access to system_server, as it is used by AlarmManagerService.

(cherry-pick of c7594898dbce021677e6444eb855eb591df1097b)

Change-Id: I8b5795cb4739bb7fb6b2673d0b1b12be40db7a7f
diff --git a/file_contexts b/file_contexts
index 9f895da..03be7b6 100644
--- a/file_contexts
+++ b/file_contexts
@@ -77,6 +77,7 @@
 /dev/random		u:object_r:random_device:s0
 /dev/rpmsg-omx[0-9]	u:object_r:rpmsg_device:s0
 /dev/rproc_user	u:object_r:rpmsg_device:s0
+/dev/rtc0           u:object_r:rtc_device:s0
 /dev/snd(/.*)?		u:object_r:audio_device:s0
 /dev/socket(/.*)?	u:object_r:socket_device:s0
 /dev/socket/adbd	u:object_r:adbd_socket:s0