crmsh-4.6: bootstrap stage should exit immediately when missing --use-ssh-agent option

[zzhou1]

1. Bootstrap a basic cluster
   adm@crmsh46-1:~> sudo -E crm cluster init --use-ssh-agent -ys /dev/disk/by-partlabel/sbd -N adm@crmsh46-2

2. then add ocfs2 stage, but forget to add --use-ssh-agent
   adm@crmsh46-1:~> sudo -E crm cluster init -y ocfs2 -o /dev/disk/by-partlabel/ocfs2
   INFO: Loading "default" profile from /etc/crm/profiles.yml
   WARNING: $SSH_AUTH_SOCK is detected. As a tip, using the --use-ssh-agent option could avoid generate local root ssh keys on cluster nodes.
   INFO: Configuring OCFS2
   WARNING: "no-quorum-policy" in crm_config is set to freeze, it was stop
   INFO: 'no-quorum-policy' is changed to "freeze"
   INFO: BEGIN Wait for DLM(ocfs2-dlm) start
   .....................................................................................................................
   ERROR: FAIL Wait for DLM(ocfs2-dlm) start
   ERROR: cluster.init: Time out waiting for resource.

[liangxin1300]

Can we change the behavior here(for the above step 2) :

• if no --use-ssh-agent option, check if $SSH_AUTH_SOCK is available and if the current cluster used ssh agent before (use this interface); if yes, set ssh agent automatically,