move log/debug codebase to libosmocore

The logging/debugging code is generic enough to move it into libosmocore
while keeping OpenBSC specific definitions in openbsc itself.

This commit uses the logging support present in libosmocore-0.1.2,
you will have to update your library to this version.
diff --git a/openbsc/src/mgcp/mgcp_main.c b/openbsc/src/mgcp/mgcp_main.c
index e45a1e9..f0640af 100644
--- a/openbsc/src/mgcp/mgcp_main.c
+++ b/openbsc/src/mgcp/mgcp_main.c
@@ -166,14 +166,14 @@
 	struct gsm_network dummy_network;
 	struct sockaddr_in addr;
 	int on = 1, rc;
-	struct debug_target *stderr_target;
+	struct log_target *stderr_target;
 
 	tall_bsc_ctx = talloc_named_const(NULL, 1, "mgcp-callagent");
 
-	debug_init();
-	stderr_target = debug_target_create_stderr();
-	debug_add_target(stderr_target);
-	debug_set_all_filter(stderr_target, 1);
+	log_init(&log_info);
+	stderr_target = log_target_create_stderr();
+	log_add_target(stderr_target);
+	log_set_all_filter(stderr_target, 1);
 
 	cfg = mgcp_config_alloc();
 	if (!cfg)