systemvm: Fix hostname is localhost in some VRs (#3422)

In some virtual routers, 'hostname -f' returns 'localhost'. The hostname is also 'localhost' in `/var/log/messages`. This change can fix the issue in new VRs.

Author: ustcweizhou

systemvm/debian/opt/cloud/bin/cs/CsDhcp.py

@@ -139,7 +139,8 @@ def delete_leases(self):
             logging.error("Caught error while trying to delete entries from dnsmasq.leases file: %s" % e)
 
     def preseed(self):
-        self.add_host("127.0.0.1", "localhost %s" % CsHelper.get_hostname())
+        self.add_host("127.0.0.1", "localhost")
+        self.add_host("127.0.1.1", "%s" % CsHelper.get_hostname())
         self.add_host("::1", "localhost ip6-localhost ip6-loopback")
         self.add_host("ff02::1", "ip6-allnodes")
         self.add_host("ff02::2", "ip6-allrouters")