osdep/language-win: remove use of GetSystemPreferredUILanguages

The system preferred language is the language used during Windows
install. It doesn't have much purpose except that it is the backend
language for core Windows internals. All user facing dialogs and text
should follow the user preferred language, as this is what the user
selected and uses on daily basis.

It makes no sense to include system language in track selection.

osdep/language-win.c

@@ -48,14 +48,6 @@ char **mp_get_user_langs(void)
     if (GetUserPreferredUILanguages(MUI_LANGUAGE_NAME, &count, buf, &size))
         apppend_langs(&ret, &ret_count, buf, count);
 
-    size = 0;
-    if (!GetSystemPreferredUILanguages(MUI_LANGUAGE_NAME, &count, NULL, &size))
-        goto done;
-
-    MP_TARRAY_GROW(NULL, buf, size);
-    if (GetSystemPreferredUILanguages(MUI_LANGUAGE_NAME, &count, buf, &size))
-        apppend_langs(&ret, &ret_count, buf, count);
-
 done:
     if (ret_count)
         MP_TARRAY_APPEND(NULL, ret, ret_count, NULL);

test/libmpv_test_track_selection.c

@@ -82,10 +82,6 @@ static bool have_english_locale(void)
     if (any_starts_with(buf, count, L"en"))
         return true;
 
-    size = _countof(buf);
-    if (!GetSystemPreferredUILanguages(MUI_LANGUAGE_NAME, &count, buf, &size))
-        fail("GetSystemPreferredUILanguages failed: %#lx\n", GetLastError());
-
     if (any_starts_with(buf, count, L"en"))
         return true;