Those directories were located in /etc/acmed/, which is not the best
choice. According to the Filesystem Hierarchy Standard, they should be
located in /var/lib/acmed/.
Because systems may have different conventions, those values are now
configuration at build time.
https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
In the Makefile, `make install` is used to create missing directories
and install files into them. Until now, the -D option was used for this
job. However, FreeBSD as an implementation of the install command that
differs about this option. In order to remain compatible with FreeBSD,
the -D option has been removed and replace by prior directory creation
using the -d option, which is common to (most?) implementations.
https://www.freebsd.org/cgi/man.cgi?query=installhttps://man.openbsd.org/installhttps://linux.die.net/man/1/install
The previous version of the Makefile used features which are specific to
GNU Make and therefore does not works on BSD systems. This new version,
which is much more simpler, works both on GNU Make and BSD Make (tested
on FreeBSD 12.1).