After 0fa5403d493be24dda2bf575c04019ef2dcc9d0c we need
usr.bin/localedef as a bootstrap tool independent on where
WITHOUT_LOCALE was specified as we ALWAYS process C.UTF-8.
At the same time LOCALES= in the local Makefile is emptyw but
C.UTF-8 with WITHOUT_LOCALES and thus after the replacement
FILES= is set to only .LC_CTYPE which results in a build failure
not knowing how to build that. Put #ifdef MK_LOCALES around and
set FILES= in case we do not want locales (but C.UTF-8).