Add generated sources dir to the default include path

Change-Id: I71fed98dfbc0bf5efad069a251eee2e5ab2e5fe6
diff --git a/core/binary.mk b/core/binary.mk
index 972a303..2bfccf4 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -703,7 +703,7 @@
 
 all_objects := $(normal_objects) $(gen_o_objects)
 
-my_c_includes += $(TOPDIR)$(LOCAL_PATH) $(intermediates)
+my_c_includes += $(TOPDIR)$(LOCAL_PATH) $(intermediates) $(generated_sources_dir)
 
 ifndef LOCAL_SDK_VERSION
   my_c_includes += $(JNI_H_INCLUDE)