[DO NOT MERGE ANYWHERE] Remove building wifi_facade with sl4n

Change-Id: I56141c92b15ae36b269d1cd31f9b2a66d5d1dc13
diff --git a/sl4n/Android.mk b/sl4n/Android.mk
index c7c0e7f..0981b97 100644
--- a/sl4n/Android.mk
+++ b/sl4n/Android.mk
@@ -30,7 +30,6 @@
 
 LOCAL_SRC_FILES := \
   facades/bluetooth/bluetooth_binder_facade.cpp \
-  facades/wifi/wifi_facade.cpp \
   main.cpp \
   utils/command_receiver.cpp \
   utils/common_utils.cpp