duplocale: Fix compilation error on Haiku (regression 2023-01-22). * lib/locale.in.h (duplocale): If HAVE_DUPLOCALE = 0, don't declare it, even if REPLACE_DUPLOCALE = 1. * modules/duplocale (Depends-on, configure.ac): Don't compile a replacement if HAVE_DUPLOCALE = 0 and REPLACE_DUPLOCALE = 1.