Do not overwrite `LANG` on NodeJS

[ilonatommy]

Currently int the non-deterministic mode LANG is overwritten by :

emscripten/src/library_wasi.js

Line 47 in fbc5d5c

var lang = ((typeof navigator == 'object' && navigator.languages && navigator.languages[0]) || 'C').replace('-', '_') + '.UTF-8';

that is okay when we are using browser. However, when we are using NodeJS that does not have navigator, we are overwritting the LANG variable. It is really problematic because we still do not have a chance to set the desired locale.
My suggestion would be to pass the process.env.LANG if it's available.

var lang = ENVIRONMENT_IS_NODE ? process.env.LANG : ((typeof navigator == 'object' && navigator.languages && navigator.languages[0]) || 'C').replace('-', '_') + '.UTF-8';

connected past issues/PRs:
#8751
#16261
#2549

[sbc100]

How about under node we just set ENV or process.env and get the entire environment reflected?

[ilonatommy]

Adressing the discussion under the PR, it would be best to set only LANG because it's the one that is overwritten. It makes the behavior consistent under both browser and node: language is chosen automatically.
The way to solve the issue that I did not see before would be to pass ENV['LANG'] with the value we would like to set.