Fix system language selection for locale aliases

[CoffeeFlux]

Fixes #211

[arch1t3cht]

As far as I can tell, this does not actually fix #211: The setup I tested had wxLocale::GetLanguageInfo(wxLocale::GetSystemLanguage())->CanonicalName returning tr_TR (hence wxLocale::GetSystemLanguage() being wxLANGUAGE_TURKISH_TURKIYE = 821) while the translation language was tr (info->Language being wxLANGUAGE_TURKISH = 819). So these differ both in CanonicalName and in Language.

AFAICT wxWidgets does not give too much information about how various languages are related but maybe additionally comparing the translation's CanonicalRef to the system language would work better? But, also, see #211 (comment) - it's quite possible that this issue is no longer as relevant as before.

[0tkl]

FYI, it works for ko-KR