Avoid setlocale bugs in tests. * modules/btowc (Dependencies): Add setlocale. * modules/c-strcase (Dependencies): Likewise. * modules/mbmemcasecmp (Dependencies): Likewise. * modules/mbmemcasecoll (Dependencies): Likewise. * modules/mbrtowc (Dependencies): Likewise. * modules/mbscasecmp (Dependencies): Likewise. * modules/mbscasestr (Dependencies): Likewise. * modules/mbschr (Dependencies): Likewise. * modules/mbscspn (Dependencies): Likewise. * modules/mbsinit (Dependencies): Likewise. * modules/mbsncasecmp (Dependencies): Likewise. * modules/mbsnrtowcs (Dependencies): Likewise. * modules/mbspbrk (Dependencies): Likewise. * modules/mbspcasecmp (Dependencies): Likewise. * modules/mbsrchr (Dependencies): Likewise. * modules/mbsrtowcs (Dependencies): Likewise. * modules/mbsspn (Dependencies): Likewise. * modules/mbsstr (Dependencies): Likewise. * modules/nl_langinfo (Dependencies): Likewise. * modules/quotearg (Dependencies): Likewise. * modules/unicase/locale-language (Dependencies): Likewise. * modules/unicase/ulc-casecmp (Dependencies): Likewise. * modules/unicase/ulc-casecoll (Dependencies): Likewise. * modules/unigbrk/ulc-grapheme-breaks (Dependencies): Likewise. * modules/unistdio/u8-vasnprintf (Dependencies): Likewise. * modules/unistdio/u16-vasnprintf (Dependencies): Likewise. * modules/unistdio/u32-vasnprintf (Dependencies): Likewise. * modules/unistdio/ulc-vasnprintf (Dependencies): Likewise. * modules/uniwbrk/ulc-wordbreaks (Dependencies): Likewise. * modules/vasnprintf-posix (Dependencies): Likewise. * modules/wcrtomb (Dependencies): Likewise. * modules/wcsnrtombs (Dependencies): Likewise. * modules/wcsrtombs (Dependencies): Likewise.