Tests failing for DMY locales

[StephanTLavavej]

@rogerorr reported to me that some of the STL's tests are failing when Windows 11 is set to an English (United Kingdom) locale with dd/MM/yyyy short date format and dd MMMM yyyy long date format (and Monday as the first day of the week, although that is probably unrelated).

The failing tests were:

• libcxx std/localization/locale.categories/category.time/locale.time.get/locale.time.get.members/date_order.pass.cpp
  • Line 33 says assert(f.date_order() == std::time_base::mdy) so failure is unsurprising.
• tr1/tests/locale3 is seeing the day and month being swapped:

  • STL/tests/tr1/tests/locale3/test.cpp

    Lines 439 to 440 in fbed7ea

    	CHECK_INT(tvec.tm_mday, 2);
    	CHECK_INT(tvec.tm_mon, 11);

• tr1/tests/locale4 has the same problem:

  • STL/tests/tr1/tests/locale4/test.cpp

    Lines 411 to 412 in fbed7ea

    	CHECK_INT(tvec.tm_mday, 2);
    	CHECK_INT(tvec.tm_mon, 11);