Revert "build/*.js: set `sourceType` to module."

This reverts commit b442ce3130.

build/.eslintrc.json

@@ -4,7 +4,7 @@
     "node": true
   },
   "parserOptions": {
-    "sourceType": "module"
+    "sourceType": "script"
   },
   "extends": "../.eslintrc.json",
   "rules": {

build/banner.js

@@ -1,3 +1,5 @@
+'use strict'
+
 const path  = require('path')
 const pkg   = require(path.resolve(__dirname, '../package.json'))
 const year  = new Date().getFullYear()

build/build-plugins.js

@@ -5,6 +5,8 @@
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  */
 
+'use strict'
+
 const path    = require('path')
 const rollup  = require('rollup')
 const babel   = require('rollup-plugin-babel')

build/change-version.js

@@ -7,6 +7,8 @@
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  */
 
+'use strict'
+
 const fs = require('fs')
 const path = require('path')
 const sh = require('shelljs')

build/generate-sri.js

@@ -10,6 +10,8 @@
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  */
 
+'use strict'
+
 const crypto = require('crypto')
 const fs = require('fs')
 const path = require('path')

build/postcss.config.js

@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = (ctx) => ({
   map: ctx.file.dirname.includes('examples') ? false : {
     inline: false,

build/rollup.config.js

@@ -1,3 +1,5 @@
+'use strict'
+
 const path    = require('path')
 const babel   = require('rollup-plugin-babel')
 const resolve = require('rollup-plugin-node-resolve')

build/vnu-jar.js

@@ -7,6 +7,8 @@
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
  */
 
+'use strict'
+
 const childProcess = require('child_process')
 const vnu = require('vnu-jar')