Hi!
JFYI: Zecke and myself have been playing around with the first steps towards a layer2 of the mobile station side.
In order to reduce code duplicaiton, we have moved a lot of header files and some code such as msgb.c, signal.c, bitvec.c and others into the library "libosmocore" (LIBrary Open Source MObile [communications] CORE).
This library resides at git://git.osmocore.org/libosmocore.git
You will have to download, compile and install the library before you can compile/install openbsc. This is done with the usual 'autoreconf -i && ./configure && make' steps.
Sorry for the minor inconvenience, but we really didn't want to have code duplication between our projects.
Regards, Harald