hal: add missing flags for extended features

- add missing feature flags and definitions
  to compile hal without extended features
  enabled.

Change-Id: I8c04ae54e6597ed43de60b2d01ca333070aef675
diff --git a/post_proc/Android.mk b/post_proc/Android.mk
index 2cb910c..c50b7d0 100644
--- a/post_proc/Android.mk
+++ b/post_proc/Android.mk
@@ -3,6 +3,10 @@
 
 include $(CLEAR_VARS)
 
+ifneq ($(strip $(AUDIO_FEATURE_DISABLED_PROXY_DEVICE)),true)
+    LOCAL_CFLAGS += -DAFE_PROXY_ENABLED
+endif
+
 LOCAL_SRC_FILES:= \
 	bundle.c \
 	equalizer.c \