split 'libosmocore' from openbsc codebase

This library is intended to collect all generic/common funcitionality
of all Osmocom.org projects, including OpenBSC but also OsmocomBB

The library currently includes the following modules:

bitvec, comp128, gsm_utils, msgb, select, signal, statistics, talloc, timer,
tlv_parse, linuxlist

msgb allocation error debugging had to be temporarily disabled as it depends on
'debug.c' functionality which at the moment remains in OpenBSC
diff --git a/openbsc/src/bts_ipaccess_nanobts.c b/openbsc/src/bts_ipaccess_nanobts.c
index 6765517..cb48ea9 100644
--- a/openbsc/src/bts_ipaccess_nanobts.c
+++ b/openbsc/src/bts_ipaccess_nanobts.c
@@ -23,7 +23,7 @@
 #include <sys/types.h>
 
 #include <openbsc/gsm_data.h>
-#include <openbsc/tlv.h>
+#include <osmocore/tlv.h>
 #include <openbsc/abis_nm.h>
 
 static struct gsm_bts_model model_nanobts = {