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/system_information.c b/openbsc/src/system_information.c
index 9bdf2c1..36dc6b9 100644
--- a/openbsc/src/system_information.c
+++ b/openbsc/src/system_information.c
@@ -31,7 +31,7 @@
 #include <openbsc/gsm_data.h>
 #include <openbsc/abis_rsl.h>
 #include <openbsc/rest_octets.h>
-#include <openbsc/bitvec.h>
+#include <osmocore/bitvec.h>
 #include <openbsc/debug.h>
 
 #define GSM48_CELL_CHAN_DESC_SIZE	16