xzdec: Use setlocale() instead of tuklib_gettext_setlocale()

xzdec: Use setlocale() instead of tuklib_gettext_setlocale()

xzdec isn't translated and doesn't need libintl on Windows even
when NLS is enabled, thus libintl_setlocale() cannot interfere
with the locale settings. Thus, standard setlocale() works perfectly.

In the commit 78868b6e, the explanation in the commit message is wrong.

Fixes: 78868b6ed63fa4c89f73e3dfed27abfb8b0d46db
(cherry picked from commit d6796f9ce5359faaaed82926c1735aee3694430f)