##### SUMMARY
The hostname module reports that it doesn't work on Manjaro Linux, eventhough this is simply an Arch based distribution. So I think it should work without any modification if Manjaro is 'whitelisted' as a platform that supports this module.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
Hostname module.

##### ANSIBLE VERSION
```ansible 2.8.3
  config file = /home/overlord/ConfigManagement/ansible/ansible.cfg
  configured module search path = ['/home/overlord/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.4 (default, Jul 16 2019, 07:12:58) [GCC 9.1.0]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```
ANSIBLE_NOCOWS = True
ANSIBLE_PIPELINING = True
ANSIBLE_SSH_ARGS = -C -o ControlMaster=auto -o ControlPersist=300s -o ServerAliveInterval=2
ANSIBLE_SSH_CONTROL_PATH = %(directory)s/%%h-%%r
ANSIBLE_SSH_CONTROL_PATH_DIR = /tmp/ansible-cp
COMMAND_WARNINGS = False
DEFAULT_ASK_PASS = True
DEFAULT_BECOME_ASK_PASS = True
DEFAULT_FORKS = 50
DEFAULT_GATHERING = smart
DEFAULT_HOST_LIST = ['/home/overlord/ConfigManagement/ansible/inventory']
DEFAULT_INTERNAL_POLL_INTERVAL = 0.005
DEFAULT_LOCAL_TMP = /tmp/ansible-local/ansible-local-13795g9m3yhv0
DEFAULT_MANAGED_STR = This file is managed by Ansible.%n
template: {file}
user: {uid}
host: {host}
DO NOT EDIT BY HAND!!!!
DEFAULT_POLL_INTERVAL = 15
DEFAULT_ROLES_PATH = ['/home/myuser/ConfigManagement/ansible/roles', '/home/myuser/ConfigManagement/ansible/galaxyroles', '/home/myuser/ConfigManagement/ansible/software']
DEFAULT_SSH_TRANSFER_METHOD = piped
DEFAULT_TIMEOUT = 30
DISPLAY_SKIPPED_HOSTS = False
HOST_KEY_CHECKING = False
RETRY_FILES_ENABLED = False
```

##### OS / ENVIRONMENT
Ansible host is Manjaro Linux (current version, all packages up-to-date) and the target host is localhost (in this case).


##### STEPS TO REPRODUCE
My task is:
```
- name: "Zorgen dat de hostname {{ baseline_hostname }} is"
  hostname:
    name: "{{ baseline_hostname }}"
```
This code works fine on Ubuntu based hosts on the same network, using the same role which includes this task.

##### EXPECTED RESULTS
It should work fine if a Manjaro host is seen by Ansible as an Arch Linux host.

##### ACTUAL RESULTS
```
fatal: [myhost.mydomain.local]: FAILED! => {"changed": false, "msg": "hostname module cannot be used on platform Linux (Manjaro)"}
```

platform = 'Linux'
    distribution = 'Fedora'
    strategy_class = SystemdStrategy
class SLESHostname(Hostname):
    platform = 'Linux'
    distribution = 'Sles'
    try:
        distribution_version = get_distribution_version()
        
        if distribution_version and 10 <= float(distribution_version) <= 12:
            strategy_class = SLESStrategy
        else:
            raise ValueError()
    except ValueError:
        strategy_class = UnimplementedStrategy
class OpenSUSEHostname(Hostname):
    platform = 'Linux'
    distribution = 'Opensuse'
    strategy_class = SystemdStrategy
class OpenSUSELeapHostname(Hostname):
    platform = 'Linux'
    distribution = 'Opensuse-leap'
    strategy_class = SystemdStrategy
class AsteraHostname(Hostname):
    platform = 'Linux'
    distribution = '"astralinuxce"'
    strategy_class = SystemdStrategy
class ArchHostname(Hostname):