Allow system server to dump netd stack traces

Bug: 144415436
Test: built, flashed, booted
      verified watchdog dumped netd stack traces during ANR

Change-Id: Ib013dd3b7e5a0fa1731559b9e056c74f30acd3cd
diff --git a/private/system_server.te b/private/system_server.te
index f0a447a..5544279 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -265,6 +265,7 @@
   mediametrics
   mediaserver
   mediaswcodec
+  netd
   sdcardd
   statsd
   surfaceflinger