Fix issue 1795088       Improve audio routing code

Initial commit for review.
Integrated comments after patch set 1 review.
Fixed lockup in AudioFlinger::ThreadBase::exit()
Fixed lockup when playing tone with AudioPlocyService startTone()
diff --git a/cmds/servicemanager/service_manager.c b/cmds/servicemanager/service_manager.c
index e4aa8b5..f3a4713 100644
--- a/cmds/servicemanager/service_manager.c
+++ b/cmds/servicemanager/service_manager.c
@@ -30,6 +30,7 @@
     { AID_MEDIA, "media.audio_flinger" },
     { AID_MEDIA, "media.player" },
     { AID_MEDIA, "media.camera" },
+    { AID_MEDIA, "media.audio_policy" },
     { AID_RADIO, "radio.phone" },
     { AID_RADIO, "radio.sms" },
     { AID_RADIO, "radio.phonesubinfo" },