Add support for LCLS to the MSC

This commit is largely based on work by
Max <msuraev@sysmocom.de>

Adds LCLS parameters for A-interface transactions
This commit also adds a vty option to facilitate globally
disabling LCLS for all calls on this MSC.

Add a global call reference (GCR) to MNCC and therefore
bump the MNCC version to version 8. (This commit has to be
merged at the same time as the corresponing commit in the
osmo-sip-connector for mncc-external use.)

Depends: osmo-sip-connector Id40d7e0fed9356f801b3627c118150055e7232b1
Change-Id: I705c860e51637b4537cad65a330ecbaaca96dd5b
diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index 170d884..72e33a6 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -260,6 +260,10 @@
 
 	/* Whether to use call waiting on the network */
 	bool call_waiting;
+
+	/* Whether to use lcls on the network */
+	bool lcls_permitted;
+
 	char *sms_db_file_path;
 };