vty: allow configuring db path from cfg file

So far, the cmdline argument was the only way to set a database file.
Add a similar config to VTY as 'msc' / 'sms-database'. The cmdline arg is stronger
than the 'database' cfg item. DB is not reloaded from VTY command.

Change-Id: I18d954c30fcceb0b36a620b927fd3a93dcc79f49
diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index 2122d4b..61fbc26 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -30,6 +30,7 @@
 struct vlr_subscr;
 struct gsup_client_mux;
 
+#define SMS_DEFAULT_DB_FILE_PATH "sms.db"
 #define tmsi_from_string(str) strtoul(str, NULL, 10)
 
 enum {
@@ -259,6 +260,7 @@
 
 	/* Whether to use call waiting on the network */
 	bool call_waiting;
+	char *sms_db_file_path;
 };
 
 struct osmo_esme;