cmdmon: refactor handling of sources report

The NSR_ReportSource() and RCL_ReportSource() functions assume that the
provided report already has some data prefilled by SRC_ReportSource()
and it's assumed these functions cannot fail.

Change them to accept the required data (refid and IP address) as
a parameter, remove unneeded parameters, and return an error status
(if the refid/address doesn't exist) to be handled in cmdmon
handle_source_data(). Also, catch unexpected values of the source state
and mode to make chronyc report an error instead of incorrect data.

refclock.c

@@ -294,23 +294,21 @@ RCL_StartRefclocks(void)
   }
 }
 
-void
-RCL_ReportSource(RPT_SourceReport *report, struct timespec *now)
+int
+RCL_ReportSource(uint32_t ref_id, RPT_SourceReport *report)
 {
   unsigned int i;
-  uint32_t ref_id;
-
-  assert(report->ip_addr.family == IPADDR_INET4);
-  ref_id = report->ip_addr.addr.in4;
 
   for (i = 0; i < ARR_GetSize(refclocks); i++) {
     RCL_Instance inst = get_refclock(i);
     if (inst->ref_id == ref_id) {
       report->poll = inst->poll;
       report->mode = RPT_LOCAL_REFERENCE;
-      break;
+      return 1;
     }
   }
+
+  return 0;
 }
 
 int