Update git submodules

Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "bifrost: Do not run virsh commands if it's not installed"
  - bifrost: Do not run virsh commands if it's not installed

    Check if 'virsh' is available before trying to remove the VMs:

    Fixes the following warning

    ./scripts/destroy-env.sh: line 36: virsh: command not found
    ./scripts/destroy-env.sh: line 37: virsh: command not found
    ./scripts/destroy-env.sh: line 36: virsh: command not found
    ./scripts/destroy-env.sh: line 37: virsh: command not found
    ./scripts/destroy-env.sh: line 36: virsh: command not found
    ./scripts/destroy-env.sh: line 37: virsh: command not found

    Change-Id: I9c82c8b8b40462584c6324871284ba12d660ae9d
    Signed-off-by: Markos Chandras <mchandras@suse.de>