made distclean depend on clean in lib Makefiles

lib/c/Makefile

@@ -6,6 +6,10 @@ all:
 	for v in $(VERSIONS) ; do $(MAKE) -C $${v} $@ || exit 1 ; done
 
 
+.PHONY: clean
+clean: 
+	for v in $(VERSIONS) ; do $(MAKE) -C $${v} $@ || exit 1 ; done
+
 .PHONY: distclean
 distclean:
 	for v in $(VERSIONS) ; do $(MAKE) -C $${v} $@ || exit 1 ; done

lib/java/Makefile

@@ -52,6 +52,6 @@ clean:
 	rm -rf gen
 
 .PHONY: distclean
-distclean:
+distclean: clean
 	rm -rf labcomm.jar labcomm2006.jar labcomm2014.jar