Postcss dynamic config doesn't work from v11.2

[chatoo2412]

Postcss dynamic config doesn't work after this commit because webpack object isn't passed anymore.
Please bring webpack object back.

And, the comment should be moved to load-postcss-config.js file.

lib/style-compiler/load-postcss-config.js:

module.exports = function loadPostcssConfig (inlineConfig) {
  if (process.env.VUE_LOADER_TEST || !loaded) {
    // use the same config loading interface as postcss-loader
    loaded = load({ webpack: webpack }, null, { argv: false }).catch(() => {
      // postcss-load-config throws error when no config file is found,
      // but for us it's optional.
    })
  }

...