Windows (MSVC, MinGW) versions of setlocale don't care about LC_*
environment variables. For example, flac cannot pass the test for
--until and --skip options the script calls it with --skip=0:01.1001
and it expects decimal comma (--skip=0:01,1001) on some locales.

Solve this (on Windows) by calling setlocale(LC_ALL, "") if some
LC_* variable is set to "C".

Patch-from: lvqcl <lvqcl.mail@gmail.com>