Fix building of layer23 against in-tree libosmocore

Hi all! As Andreas has pointed out to me in a phone call yesterday and steve-m mentioned on IRC: Building layer23 with the not-installed (make install) libosmocore from osmocom-bb resulted in link failures. I've now addressed those problems and the repo should be building just fine again. Regards, Harald. -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)