audiopolicy: add Volume Group introspection APIs

Change-Id: Ib02900bde69ee24685d9d374c0e5f73d33fa59e7
Signed-off-by: François Gaffie <francois.gaffie@renault.com>

Test: make
Bug: 124767636
diff --git a/media/libaudioclient/Android.bp b/media/libaudioclient/Android.bp
index b111b78..e9b6fb1 100644
--- a/media/libaudioclient/Android.bp
+++ b/media/libaudioclient/Android.bp
@@ -10,6 +10,7 @@
         "AudioAttributes.cpp",
         "AudioPolicy.cpp",
         "AudioProductStrategy.cpp",
+        "AudioVolumeGroup.cpp",
     ],
     shared_libs: [
         "libaudioutils",