errlog: eltc() re-add flush

Removal upsets dbCaLinkTest on RTEMS, which must not be
synchronizing correctly.  Re-add until this can be corrected.

modules/libcom/src/error/errlog.c

@@ -353,6 +353,7 @@ int eltc(int yesno)
     epicsMutexMustLock(pvt.msgQueueLock);
     pvt.toConsole = yesno;
     epicsMutexUnlock(pvt.msgQueueLock);
+    errlogFlush();
     return 0;
 }