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/media/libmedia/Android.mk b/media/libmedia/Android.mk
index 07c81f7..9d442c3 100644
--- a/media/libmedia/Android.mk
+++ b/media/libmedia/Android.mk
@@ -20,7 +20,8 @@
     mediametadataretriever.cpp \
     ToneGenerator.cpp \
     JetPlayer.cpp \
-    IOMX.cpp
+    IOMX.cpp \
+ 	IAudioPolicyService.cpp
 
 LOCAL_SHARED_LIBRARIES := \
 	libui libcutils libutils libbinder libsonivox