Place the Javadoc output in its own directory
--- RXTX.orig/Makefile.am
+++ RXTX/Makefile.am
@@ -99,7 +99,8 @@
 
 #  create the javadoc files.
 docs: $(CLASSES)
-	$(JAVADOC) $(javafiles)
+	mkdir javadoc
+	cd javadoc && $(JAVADOC) $(javafiles)
 
 ################  WIN32 CrossCompiling from here down #######################