Do not run updateservice tests, when tests are disabled. Bug 359701, r=benjamin

toolkit/mozapps/update/src/Makefile.in

@@ -60,5 +60,7 @@ include $(topsrcdir)/config/rules.mk
 nsUpdateService.js: nsUpdateService.js.in
 	$(PERL) $(MOZILLA_DIR)/config/preprocessor.pl $(DEFINES) $(ACDEFINES) $^ > $@ 
 
+ifdef ENABLE_TESTS
 check:: nsUpdateService.js
 	$(CYGWIN_WRAPPER) $(RUN_TEST_PROGRAM) $(DIST)/bin/xpcshell$(BIN_SUFFIX) -f nsUpdateService.js $(srcdir)/testnsUpdateService.js
+endif