snapshotctl: allow to write stats

To send statistics about snapshot merge times, snapshotctl will take
care of packing and sending all the information.
Allow snapshotctl to do so by creating an sepolicy exception.

Bug: 138817833
Test: statsd_testdrive
Change-Id: If805a522898cb6c9838779be23df6078f77d0cdc
Signed-off-by: Alessio Balsini <balsini@google.com>
diff --git a/private/snapshotctl.te b/private/snapshotctl.te
index f8399fe..fb2bbca 100644
--- a/private/snapshotctl.te
+++ b/private/snapshotctl.te
@@ -35,6 +35,9 @@
 hwbinder_use(snapshotctl)
 hal_client_domain(snapshotctl, hal_bootctl)
 
+# Allow snapshotctl to write to statsd socket.
+unix_socket_send(snapshotctl, statsdw, statsd)
+
 # Logging
 userdebug_or_eng(`
   allow snapshotctl snapshotctl_log_data_file:dir rw_dir_perms;