ios_facts: Add check to skip lldp neighbors if lldp doesn't exist or isn't enabled.

[tyler-8]

SUMMARY

Fixes #37507

Older IOS devices that don't support LLDP fail when including interfaces as part of ios_facts. This commit adds a check for any IOS errors when running the command show lldp and skips the LLDP neighbor parsing if LLDP isn't available.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

ios_facts

ANSIBLE VERSION

ansible 2.6.0 (devel ddf7873d6e) last updated 2018/05/14 16:49:20 (GMT -400)
  config file = /Users/tyler8/projects/pycon18/projfiles/ansible.cfg
  configured module search path = ['/Users/tyler8/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/tyler8/projects/pycon18/ansible/lib/ansible
  executable location = /Users/tyler8/.local/share/virtualenvs/pycon18-CTYMJGfK/bin/ansible
  python version = 3.6.5 (default, Mar 30 2018, 06:41:53) [GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)]

ADDITIONAL INFORMATION

- hosts: csr
  gather_facts: no
  connection: network_cli

  tasks:

  - name: IOS | Get the facts
    ios_facts:
      gather_subset: all
    register: thefacts

  - debug: msg="{{ thefacts }}"

With LLDP enabled with no neighbors:

            "ansible_net_model": "CSR1000V",
            "ansible_net_neighbors": {
                "null": [
                    {
                        "host": null,
                        "port": null
                    }
                ]
            },
            "ansible_net_serialnum": "1234QWERTY",

With no LLDP enabled (should be same for no LLDP support:

            "ansible_net_model": "CSR1000V",
            "ansible_net_serialnum": "1234QWERTY",

I don't have the ability to test on a device that doesn't support LLDP at all - however the check logic should be the same regardless if the error string is present.

[ansibot]

cc @privateip @rcarrillocruz
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[tyler-8]

Closing for now as the issue is higher up in the IOS logic and was actually a regression since ansible/ansible-modules-core#5491

[Qalthos]

Hey, this actually is almost right, give me a minute

[ansibot]

cc @ganeshrn @gdpak @gundalow @trishnaguha
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[Qalthos]

Oh no, you rebased and removed my commit. I can add it back on, but you'll need to pull afterwards.