The PR itself looks ok to be merged.
Indeed we may have to alter some of the link stuff of `kamailio` and `kamcmd` as noted by @drTr0jan for proper `FreeBSD` support.
Regarding the https://github.com/kamailio/kamailio/blob/6b0b8cb84b7d0e965d50bdf0dfa5423004..., it will probably go away and just define it per OS like it was in the makefiles.