Remove an unsed include dir

Change-Id: I05aa1e7e0639a5ec5576bf7646f35d2e5b157c09
diff --git a/libc/Android.mk b/libc/Android.mk
index b2ac9af..0a4958e 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -446,7 +446,6 @@
 libc_common_c_includes := \
     $(LOCAL_PATH)/stdlib  \
     $(LOCAL_PATH)/stdio   \
-    external/safe-iop/include
 
 # ========================================================
 # Add in the arch-specific flags.