Makefile: pass few targets at once

Be green -- save bytes!
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -174,9 +174,7 @@ clean: clean-built
 	$(Q) $(RM) -r ./gcov
 	$(Q) $(RM) -r ./test/lib/
 	$(Q) $(RM) -r ./test/lib64/
-	$(Q) $(MAKE) -C test/zdtm cleandep
-	$(Q) $(MAKE) -C test/zdtm clean
-	$(Q) $(MAKE) -C test/zdtm cleanout
+	$(Q) $(MAKE) -C test/zdtm cleandep clean cleanout
 
 distclean: clean
 	$(E) "  DISTCLEAN"