Implement audio routing callbacks

Implement JNI for AudioTrack and AudioRecord routing
callbacks:
- Added files core/jni/android_media_DeviceCallback.cpp/.h
for JNI callback implementation used by both AudioTrack
and AudioRecord.
- Made AudioManager AudioPort and AudioPatch methods static
in order to call them without context.

Also added IO handle information to AudioMixPort.

Change-Id: Icee182aa68310d4b12fd1469f48e78110889acf1
diff --git a/core/jni/Android.mk b/core/jni/Android.mk
index bbdd860..5448214 100644
--- a/core/jni/Android.mk
+++ b/core/jni/Android.mk
@@ -132,6 +132,7 @@
     android_media_AudioRecord.cpp \
     android_media_AudioSystem.cpp \
     android_media_AudioTrack.cpp \
+    android_media_DeviceCallback.cpp \
     android_media_JetPlayer.cpp \
     android_media_RemoteDisplay.cpp \
     android_media_ToneGenerator.cpp \