scripts/travis/Makefile: mark phony target as such

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

scripts/travis/Makefile

 local:
 	./travis-tests
+.PHONY: local
+
 %:
 	$(MAKE) -C ../build $@