post_proc: Support effects in DSP for tunnel mode playback

Add interface to support configuring equlaizer, bass boost,
virtualizer and reverb effects in DSP for tunnel mode of
playback.

Change-Id: I9a93ad6136c4de06df5136967908b4e888dae44f
diff --git a/Android.mk b/Android.mk
index 0e94762..424bbe1 100644
--- a/Android.mk
+++ b/Android.mk
@@ -11,6 +11,7 @@
 include $(MY_LOCAL_PATH)/policy_hal/Android.mk
 include $(MY_LOCAL_PATH)/visualizer/Android.mk
 include $(MY_LOCAL_PATH)/audiod/Android.mk
+include $(MY_LOCAL_PATH)/post_proc/Android.mk
 endif
 
 endif