wcsmbs: Add missing test-c8rtomb/test-mbrtoc8 dependency

Make test-c8rtomb.out and test-mbrtoc8.out depend on $(gen-locales) for

  xsetlocale (LC_ALL, "de_DE.UTF-8");
  xsetlocale (LC_ALL, "zh_HK.BIG5-HKSCS");

Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>