it has been deprecated in libosmocore.git 2.5 years ago:
commit 7e0686c6b4b456ec4e6e15689694b1bcf96c301f
Author: Neels Hofmeyr <neels@hofmeyr.de>
Date: Mon Sep 10 20:58:52 2018 +0200
Change-Id: Ieb9e958278e7bb9d5e798f83b70dcb873a25d06d
In libosmocore I34b8fde2955ecc010d1dcd9512e1bba9211e2c0d we introduced
a new log subsystem; enabel it in the related configs here
Change-Id: Ie3d178e68aa81d5636c87940074cb6582ac2f131