Update to new WebRTC version

* Update include/ path
* Remove unnecessary casts

Change-Id: Iac2cf15ee4fce32bcd7ad57b3e0f70976cf89880
diff --git a/media/libeffects/preprocessing/Android.mk b/media/libeffects/preprocessing/Android.mk
index 82415d5..4e4b094 100644
--- a/media/libeffects/preprocessing/Android.mk
+++ b/media/libeffects/preprocessing/Android.mk
@@ -12,7 +12,7 @@
 
 LOCAL_C_INCLUDES += \
     external/webrtc \
-    external/webrtc/webrtc/modules/interface \
+    external/webrtc/webrtc/modules/include \
     external/webrtc/webrtc/modules/audio_processing/include \
     $(call include-path-for, audio-effects)