Addition of developer and user modes to debugcli

In order to be able to protect the interface so that mistyped argument
do not endanger MaxScale yet still allow the developer access a router
option has been added that gives the debugcli two modes.

server/core/dcb.c

@@ -1606,3 +1606,31 @@ DCB_CALLBACK	*cb, *nextcb;
 	}
 	spinlock_release(&dcb->cb_lock);
 }
+
+/**
+ * Check the passed DCB to ensure it is in the list of allDCBS
+ *
+ * @param	DCB	The DCB to check
+ * @return	1 if the DCB is in the list, otherwise 0
+ */
+int
+dcb_isvalid(DCB *dcb)
+{
+DCB	*ptr;
+int	rval = 0;
+
+	spinlock_acquire(&dcbspin);
+	ptr = allDCBs;
+	while (ptr)
+	{
+		if (ptr == dcb)
+		{
+			rval = 1;
+			break;
+		}
+		ptr = ptr->next;
+	}
+	spinlock_release(&dcbspin);
+
+	return rval;
+}