Fix dependencies around tools/*-event-log-tags.py

We should regenerate merged tag files and java sources when
these scripts are updated.

Change-Id: Id5f11d6f480f3f74dab08f01e929ee2d7fafd2d0
diff --git a/core/definitions.mk b/core/definitions.mk
index 5a91045..ce71f45 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1082,7 +1082,7 @@
 define transform-logtags-to-java
 @mkdir -p $(dir $@)
 @echo "logtags: $@ <= $<"
-$(hide) $(JAVATAGS) -o $@ $^
+$(hide) $(JAVATAGS) -o $@ $< $(PRIVATE_MERGED_TAG)
 endef