i18n: detect UI language without POSIX-style locale variable on Windows (BC) On Windows, it isn't common to set LANG environment variable. This patch makes gettext honor Windows-style UI language [1] if no locale variables are set. Because of this change, LANG=C or HGPLAIN must be set in order to disable translation on non-English Windows. [1]: http://msdn.microsoft.com/en-us/library/dd374098(v=VS.85).aspx