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/rest_octets.c b/openbsc/src/rest_octets.c
index 74874bd..a57e7df 100644
--- a/openbsc/src/rest_octets.c
+++ b/openbsc/src/rest_octets.c
@@ -27,7 +27,7 @@
 #include <errno.h>
 
 #include <openbsc/gsm_data.h>
-#include <openbsc/bitvec.h>
+#include <osmocore/bitvec.h>
 #include <openbsc/rest_octets.h>
 
 /* generate SI1 rest octets */