Fixed a build error of audio conference mixer in Android.
Review URL: http://webrtc-codereview.appspot.com/267009

git-svn-id: http://webrtc.googlecode.com/svn/trunk@936 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/src/modules/audio_conference_mixer/source/Android.mk b/src/modules/audio_conference_mixer/source/Android.mk
index da56e8b..ead9d0f 100644
--- a/src/modules/audio_conference_mixer/source/Android.mk
+++ b/src/modules/audio_conference_mixer/source/Android.mk
@@ -29,6 +29,7 @@
 LOCAL_C_INCLUDES := \
     $(LOCAL_PATH)/../interface \
     $(LOCAL_PATH)/../../interface \
+    $(LOCAL_PATH)/../../audio_processing/interface \
     $(LOCAL_PATH)/../../.. \
     $(LOCAL_PATH)/../../../system_wrappers/interface