ctld: Consistently use item count as the first argument to calloc

Reported by: GCC 14 -Wcalloc-transposed-args
Reviewed by: rlibby, imp, emaste
Differential Revision: https://reviews.freebsd.org/D46013

(cherry picked from commit 2ba12978f67432a3f88b17704391d28e1fc0e788)