2013-03-16 was not the date Emacs 24.3 was released, it was not even the date on which I merged all changes from that release into trunk. Ref: http://lists.gnu.org/archive/html/emacs-devel/2013-03/msg00990.html
This directory contains the source code for the architecture-dependent
files that go in ${archlibdir}. At present, these are mostly utility
programs used by GNU Emacs.