On some recent Windows systems, ext\pcre\tests\locales.phpt fails, because 'pt_PT' is accepted by `setlocale()`, but not properly supported by the ctype functions, which are used internally by PCRE2 to build the localized character tables. Since there appears to be no way to properly check whether a given locale is fully supported, but we want to minimize BC impact, we filter out typical Unix locale names, except for a few cases which have already been properly supported on Windows. This way code like setlocale(LC_ALL, 'de_DE.UTF-8', 'de_DE', 'German_Germany.1252'); should work like on older Windows systems. It should be noted that the locale names causing trouble are not (yet) documented as valid names anyway, see <https://docs.microsoft.com/en-us/cpp/c-runtime-library/locale-names-languages-and-country-region-strings?view=vs-2019>.