version_policy: avoid fclose a NULL file pointer

Test: Pass a not cil file to version_policy and see no crash appeared.
example: out/host/linux-x86/bin/version_policy -b  `which ls`  -m -n 10000.0 -o target

Change-Id: If2b950a02dd94a4813b74377617f90c7a75a9f27
Signed-off-by: liwugang <liwugang@xiaomi.com>
diff --git a/tools/version_policy.c b/tools/version_policy.c
index 8848190..8bb422a 100644
--- a/tools/version_policy.c
+++ b/tools/version_policy.c
@@ -65,14 +65,15 @@
 	rc = cil_add_file(*db, path, buff, file_size);
 	if (rc != SEPOL_OK) {
 		fprintf(stderr, "Failure adding %s to parse tree\n", path);
-		goto err;
+		goto parse_err;
 	}
 	free(buff);
 
 	return SEPOL_OK;
 err:
-	free(buff);
 	fclose(file);
+parse_err:
+	free(buff);
 file_err:
 	cil_db_destroy(db);
 	return rc;