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##### SUMMARY
When i collect facts from TrueNAS, with the command : `ansible truenas -m setup | grep "ansible_distribution"`
the variable "ansible_distribution_major_version" is missing.
When i use same command on debian host, the variable is stell here

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/module_utils/facts

##### ANSIBLE VERSION
```
ansible 2.10.2
  config file = /srv/ansible/ansible.cfg
  configured module search path = ['/srv/ansible/library']
  ansible python module location = /srv/ansible-venv/lib/python3.7/site-packages/ansible
  executable location = /srv/ansible-venv/bin/ansible
  python version = 3.7.3 (default, Dec 20 2019, 18:57:59) [GCC 8.3.0]
```

##### CONFIGURATION
<!--- Paste verbatim output from "" between quotes -->
```
ANSIBLE_FORCE_COLOR(/srv/ansible/ansible.cfg) = True
DEFAULT_HOST_LIST(/srv/ansible/ansible.cfg) = ['/srv/ansible/site.host']
DEFAULT_JINJA2_EXTENSIONS(/srv/ansible/ansible.cfg) = jinja2.ext.do
DEFAULT_MANAGED_STR(/srv/ansible/ansible.cfg) = Gestion par Ansible: {file} modifie le %Y-%m-%d %H:%M:%S par {uid} depuis {host}
DEFAULT_MODULE_PATH(/srv/ansible/ansible.cfg) = ['/srv/ansible/library']
DEFAULT_ROLES_PATH(/srv/ansible/ansible.cfg) = ['/srv/ansible/roles']
DEFAULT_STDOUT_CALLBACK(/srv/ansible/ansible.cfg) = yaml
DISPLAY_SKIPPED_HOSTS(/srv/ansible/ansible.cfg) = False
INTERPRETER_PYTHON(/srv/ansible/ansible.cfg) = auto_silent
RETRY_FILES_ENABLED(/srv/ansible/ansible.cfg) = False

```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->


##### STEPS TO REPRODUCE
ansible truenas -m setup | grep "ansible_distribution"

##### EXPECTED RESULTS
```
...
        "ansible_distribution": "FreeBSD",
        "ansible_distribution_release": "12.2-RC3",
        "ansible_distribution_major_version": "12",
        "ansible_distribution_version": "FreeBSD 12.2-RC3 7c4ec6ff02c(HEAD) TRUENAS",
...
```


##### ACTUAL RESULTS
```
...
        "ansible_distribution": "FreeBSD",
        "ansible_distribution_release": "12.2-RC3",
        "ansible_distribution_version": "FreeBSD 12.2-RC3 7c4ec6ff02c(HEAD) TRUENAS",
...
```

OS_FAMILY_MAP = {'RedHat': ['RedHat', 'Fedora', 'CentOS', 'Scientific', 'SLC',
                                'Ascendos', 'CloudLinux', 'PSBM', 'OracleLinux', 'OVS',
                                'OEL', 'Amazon', 'Virtuozzo', 'XenServer', 'Alibaba',
                                'EulerOS', 'openEuler'],
                     'Debian': ['Debian', 'Ubuntu', 'Raspbian', 'Neon', 'KDE neon',
                                'Linux Mint', 'SteamOS', 'Devuan', 'Kali', 'Cumulus Linux',
                                'Pop!_OS', 'Parrot', 'Pardus GNU/Linux'],
                     'Suse': ['SuSE', 'SLES', 'SLED', 'openSUSE', 'openSUSE Tumbleweed',
                              'SLES_SAP', 'SUSE_LINUX', 'openSUSE Leap'],
                     'Archlinux': ['Archlinux', 'Antergos', 'Manjaro'],
                     'Mandrake': ['Mandrake', 'Mandriva'],
                     'Solaris': ['Solaris', 'Nexenta', 'OmniOS', 'OpenIndiana', 'SmartOS'],
                     'Slackware': ['Slackware'],
                     'Altlinux': ['Altlinux'],
                     'SGML': ['SGML'],
                     'Gentoo': ['Gentoo', 'Funtoo'],
                     'Alpine': ['Alpine'],
                     'AIX': ['AIX'],
                     'HP-UX': ['HPUX'],
                     'Darwin': ['MacOSX'],
                     'FreeBSD': ['FreeBSD', 'TrueOS'],
                     'ClearLinux': ['Clear Linux OS', 'Clear Linux Mix'],
                     'DragonFly': ['DragonflyBSD', 'DragonFlyBSD', 'Gentoo/DragonflyBSD', 'Gentoo/DragonFlyBSD'],
                     'NetBSD': ['NetBSD'], }
    OS_FAMILY = {}
    for family, names in OS_FAMILY_MAP.items():
        for name in names:
            OS_FAMILY[name] = family
    def __init__(self, module):