MT#55283 prevent erroneous swithch to DB 0

A call that gets created but then doesn't get initialised would have its
Redis DB left at zero. At destruction it would then try to switch to DB
zero. Fix this by using an appropriate initial value.

Closes #1905

Change-Id: I852e48c5a06b732b37d2ccd5c478de4760aacd4e

daemon/call.c

@@ -4331,6 +4331,7 @@ static call_t *call_create(const str *callid) {
 	c->tos = rtpe_config.default_tos;
 	c->poller = rtpe_get_poller();
 	c->sdp_fragments = fragments_ht_new();
+	c->redis_hosted_db = -1;
 	if (rtpe_config.cpu_affinity)
 		c->cpu_affinity = call_socket_cpu_affinity++ % rtpe_config.cpu_affinity;
 	else

include/call.h

@@ -766,7 +766,7 @@ struct call {
 	sockaddr_t		xmlrpc_callback;
 	endpoint_t		dtmf_log_dest;
 
-	unsigned int		redis_hosted_db;
+	int			redis_hosted_db;
 	atomic64		last_redis_update;
 
 	struct recording 	*recording;