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/libosmocore/include/osmocore/signal.h b/libosmocore/include/osmocore/signal.h
new file mode 100644
index 0000000..02d83d2
--- /dev/null
+++ b/libosmocore/include/osmocore/signal.h
@@ -0,0 +1,15 @@
+#ifndef OSMOCORE_SIGNAL_H
+#define OSMOCORE_SIGNAL_H
+
+typedef int signal_cbfn(unsigned int subsys, unsigned int signal,
+			void *handler_data, void *signal_data);
+
+
+/* Management */
+int register_signal_handler(unsigned int subsys, signal_cbfn *cbfn, void *data);
+void unregister_signal_handler(unsigned int subsys, signal_cbfn *cbfn, void *data);
+
+/* Dispatch */
+void dispatch_signal(unsigned int subsys, unsigned int signal, void *signal_data);
+
+#endif /* OSMOCORE_SIGNAL_H */