On Windows 8.1, HexChat doesn't detect OS language and chooses English by default

[stil]

Hi, I just wanted to tell, that HexChat on Windows 8.1 doesn't detect operating system language. It is always English by default. Of course it can be changed in Preferences, but I think that fixing it wouldn't be very difficult. I noticed, that HexChat properly detects language of spelling dictionary if it does matter.

I forgot to mention: version 2.10.0

[TingPing]

Spell check gets this info via g_get_language_names the interface only reads some env variables not used on Windows, so likely that could just be reused for both (though I thought the glib function only used env variables too...).

[Arnavion]

Duplicate of #473