Add test_cmdline.sh to distribution.

src/test/include.am

@@ -413,7 +413,8 @@ EXTRA_DIST += \
 	src/test/test_workqueue_efd2.sh \
 	src/test/test_workqueue_pipe.sh \
 	src/test/test_workqueue_pipe2.sh \
-	src/test/test_workqueue_socketpair.sh
+	src/test/test_workqueue_socketpair.sh \
+	src/test/test_cmdline.sh
 
 test-rust:
 	$(TESTS_ENVIRONMENT) "$(abs_top_srcdir)/src/test/test_rust.sh"