Add missing newline to pipe test

Original patch by Ben Larson <hungryninja101@gmail.com>.

Fixes #3055

repos/libports/src/test/libc_pipe/main.cc

@@ -76,7 +76,7 @@ int main(int argc, char *argv[])
 	ssize_t bytes_written = write(pipefd[1], buf, BUF_SIZE);
 
 	if (bytes_written != BUF_SIZE) {
-		fprintf(stderr, "Error writing to pipe");
+		fprintf(stderr, "Error writing to pipe\n");
 		exit(1);
 	}