Revert "Clear LOCAL_RTTI_FLAG."

This reverts commit f524df7ce1a5e276607563272fa1838967a4a239.
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index bc085f5..ab6efd4 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -42,7 +42,6 @@
 LOCAL_ASFLAGS:=
 LOCAL_CFLAGS:=
 LOCAL_CPPFLAGS:=
-LOCAL_RTTI_FLAG:=
 LOCAL_C_INCLUDES:=
 LOCAL_LDFLAGS:=
 LOCAL_LDLIBS:=