fix missing exit value for kill cmd

Author: Yang Guo

platform-agent/src/main/java/com/flow/platform/agent/CmdManager.java

@@ -260,6 +260,7 @@ public synchronized void kill() {
             CmdResult r = entry.getValue();
             r.setExecutedTime(now);
             r.setFinishTime(now);
+            r.setExitValue(CmdResult.EXIT_VALUE_FOR_KILL);
 
             Cmd cmd = entry.getKey();
             finished.put(cmd, r);