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/vty/command.c b/openbsc/src/vty/command.c
index 5b1dcb9..2faed35 100644
--- a/openbsc/src/vty/command.c
+++ b/openbsc/src/vty/command.c
@@ -47,7 +47,7 @@
 
 #include <openbsc/gsm_data.h>
 #include <openbsc/gsm_subscriber.h>
-#include <openbsc/talloc.h>
+#include <osmocore/talloc.h>
 
 void *tall_vty_cmd_ctx;