Hi,
AFAICS PREDEFINED_CLASSES is never defined thus the code is unused. It would seem that the code is related to LO_LTYPE which was discussed in the past but there are no any recent references:
http://pubs.opengroup.org/onlinepubs/9638399/loltype.htm
Patch below, compiles and passes make check.
2015-05-12 Marko Myllynen <myllynen@redhat.com>
* locale/C-ctype.c (PREDEFINED_CLASSES): Remove.
* locale/programs/ld-ctype.c: Likewise.