fix($build): do not pick "babel.config.js" at user-land (close: #797)

lib/webpack/createBaseConfig.js

@@ -166,8 +166,11 @@ module.exports = function createBaseConfig ({
         .use('babel-loader')
           .loader('babel-loader')
           .options({
-            // do not pick local project babel config
+            // do not pick local project babel config (.babelrc)
             babelrc: false,
+            // do not pick local project babel config (babel.config.js)
+            // ref: http://babeljs.io/docs/en/config-files
+            configFile: false,
             presets: [
               require.resolve('@vue/babel-preset-app')
             ]