It is the same version of libosmocore that comes with osmocombb.
https://osmocom.org/projects/baseband/wiki/Software_Getting_Started#Dependen...
For osmocomBB, as for several other osmocom projects, you will also need libosmocore. Note: Although libosmocore is included when getting osmocom-bb from the git repository, you have to install it separately. The libosmocore subtree is only used to compile the embedded ARM version of libosmocore.
With best regards, Vadim Yanitskiy.