test: fix some memory leaks

test/ds/unicode-strings.c

@@ -21,6 +21,7 @@ int main(void)
 		printf("%s\n", tok);
 	}
 	b_iterator_unref(it);
+	b_string_unref(str);
 
 	return 0;
 }

test/io/streams.c

@@ -19,5 +19,8 @@ int main(int argc, const char **argv)
 	b_stream_read_all_bytes_s(b_stdin, dest, buf, &nr_read);
 
 	printf("done. read %zu bytes total.\n", nr_read);
+
+	b_path_unref(path);
+	b_file_unref(dest);
 	return 0;
 }