Clear LOCAL_RTTI_FLAG.

Change-Id: I0f1388e76af1ce0592cd3271a689fbb6c0ea3eba
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index ab6efd4..bc085f5 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -42,6 +42,7 @@
 LOCAL_ASFLAGS:=
 LOCAL_CFLAGS:=
 LOCAL_CPPFLAGS:=
+LOCAL_RTTI_FLAG:=
 LOCAL_C_INCLUDES:=
 LOCAL_LDFLAGS:=
 LOCAL_LDLIBS:=