Buffer Log functionality for AudioFlinger

Similar to ALOGV, this allows to capture to file audio samples from
within audioservice for debuggin purposes.

Test: manual. Mostly used for debugging
Change-Id: I4d43f573926805a27be910e343476c3f1be51579
diff --git a/services/audioflinger/Android.mk b/services/audioflinger/Android.mk
index f35373f..1657c08 100644
--- a/services/audioflinger/Android.mk
+++ b/services/audioflinger/Android.mk
@@ -31,7 +31,8 @@
     AudioMixer.cpp.arm          \
     BufferProviders.cpp         \
     PatchPanel.cpp              \
-    StateQueue.cpp
+    StateQueue.cpp              \
+    BufLog.cpp
 
 LOCAL_C_INCLUDES := \
     $(TOPDIR)frameworks/av/services/audiopolicy \