Allow update engine to write to statsd socket

Update_engine reports metrics with libmerticslogger, which switches to
write to statsd recently. Add the permission to update_engine_common so
that both the daemon and recovery sideload tool can report the metrics.

update_engine: type=1400 audit(0.0:47): avc: denied { write } for name="statsdw" dev="tmpfs" ino=26257 scontext=u:r:update_engine:s0 tcontext=u:object_r:statsdw_socket:s0 tclass=sock_file permissive=0
update_engine: type=1400 audit(0.0:54): avc: denied { write } for name="statsdw" dev="tmpfs" ino=26257 scontext=u:r:update_engine:s0 tcontext=u:object_r:statsdw_socket:s0 tclass=sock_file permissive=0

Bug: 120623435
Test: the denial message disappear
Change-Id: Ie6a7a179b4291ef8209c99de758862b25df2a02f
1 file changed