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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",
...
```

self.module = module
    def get_distribution_facts(self):
        distribution_facts = {}
        
        
        
        system = platform.system()
        distribution_facts['distribution'] = system
        distribution_facts['distribution_release'] = platform.release()
        distribution_facts['distribution_version'] = platform.version()
        systems_implemented = ('AIX', 'HP-UX', 'Darwin', 'FreeBSD', 'OpenBSD', 'SunOS', 'DragonFly', 'NetBSD')
        if system in systems_implemented:
            cleanedname = system.replace('-', '')
            distfunc = getattr(self, 'get_distribution_' + cleanedname)
            dist_func_facts = distfunc()
            distribution_facts.update(dist_func_facts)
        elif system == 'Linux':
            distribution_files = DistributionFiles(module=self.module)
            
            dist_file_facts = distribution_files.process_dist_files()
            distribution_facts.update(dist_file_facts)
        distro = distribution_facts['distribution']
        
        distribution_facts['os_family'] = self.OS_FAMILY.get(distro, None) or distro
        return distribution_facts
    def get_distribution_AIX(self):