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/gsm_04_08_utils.c b/openbsc/src/gsm_04_08_utils.c
index 821bde2..53c57ca 100644
--- a/openbsc/src/gsm_04_08_utils.c
+++ b/openbsc/src/gsm_04_08_utils.c
@@ -28,7 +28,7 @@
 #include <errno.h>
 #include <netinet/in.h>
 
-#include <openbsc/msgb.h>
+#include <osmocore/msgb.h>
 #include <openbsc/debug.h>
 #include <openbsc/gsm_04_08.h>
 #include <openbsc/transaction.h>