Make sort locale independent

Re: npm/cli#2829

PR-URL: #5
Credit: @padinko
Close: #5
Reviewed-by: @isaacs

EDIT(@isaacs): added tests

index.js

@@ -5,7 +5,7 @@ const compare = (ak, bk, prefKeys) =>
   : prefKeys.includes(bk) && !prefKeys.includes(ak) ? 1
   : prefKeys.includes(ak) && prefKeys.includes(bk)
     ? prefKeys.indexOf(ak) - prefKeys.indexOf(bk)
-    : ak.localeCompare(bk)
+    : ak.localeCompare(bk, 'en')
 
 const sort = (replacer, seen) => (key, val) => {
   const prefKeys = Array.isArray(replacer) ? replacer : []

package.json

@@ -17,6 +17,9 @@
     "postpublish": "git push origin --follow-tags"
   },
   "tap": {
+    "test-env": [
+      "LC_ALL=sk"
+    ],
     "check-coverage": true
   },
   "devDependencies": {

tap-snapshots/test/basic.js.test.cjs

@@ -7,6 +7,9 @@
 'use strict'
 exports[`test/basic.js TAP basic sorting operation with default 2-space indent > mix of objects and out of order keys 1`] = `
 {
+  "c": 1,
+  "ch": 2,
+  "d": 3,
   "y": "z",
   "yy": "a",
   "z": 1,

test/basic.js

@@ -4,6 +4,9 @@ const stringify = require('../')
 t.test('basic sorting operation with default 2-space indent', t => {
   t.plan(1)
   t.matchSnapshot(stringify({
+    c: 1,
+    ch: 2,
+    d: 3,
     z: 1,
     y: 'z',
     obj: { a: {}, b: 'x' },