Remove outdated distribute dependency

[jaylinski]

Description

As stated on PyPi (https://pypi.org/project/distribute/),
distribute is a legacy package and compatibility layer
that installs Setuptools 0.7+.

Since Setuptools (v41) gets already installed, this wrapper
is not needed anymore.

Related to #12804.

Original commit that introduced distribute 7 years ago: 885a60e

Motivation and Context

The distribute version used in Kodi is from 2011 (https://pypi.org/project/distribute/0.6.21/), was last updated in 2013 and doesn't even support the current Python version (3.8).

This PR also fixes a depends-build error I experience on Ubuntu 18.04:

Setuptools installation detected at /opt/xbmc-deps/x86_64-linux-gnu-native/lib/python3.7/site-packages/setuptools-41.0.1.post20200209-py3.7.egg
Not patching, --root or --prefix is installing Distribute in another location
running install
Traceback (most recent call last):
  File "setup.py", line 211, in <module>
    scripts = scripts,
  File "/opt/xbmc-deps/x86_64-linux-gnu-native/lib/python3.7/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/opt/xbmc-deps/x86_64-linux-gnu-native/lib/python3.7/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/opt/xbmc-deps/x86_64-linux-gnu-native/lib/python3.7/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "build/src/setuptools/command/install.py", line 73, in run
    self.do_egg_install()
  File "build/src/setuptools/command/install.py", line 82, in do_egg_install
    easy_install = self.distribution.get_command_class('easy_install')
  File "build/src/setuptools/dist.py", line 362, in get_command_class
    self.cmdclass[command] = cmdclass = ep.load()
  File "build/src/pkg_resources.py", line 1992, in load
    entry = __import__(self.module_name, globals(),globals(), ['__name__'])
  File "build/src/setuptools/command/easy_install.py", line 25, in <module>
    from setuptools.package_index import PackageIndex
  File "build/src/setuptools/package_index.py", line 157, in <module>
    sys.version[:3], require('distribute')[0].version
  File "build/src/pkg_resources.py", line 686, in require
    needed = self.resolve(parse_requirements(requirements))
  File "build/src/pkg_resources.py", line 584, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: distribute
Makefile:22: recipe for target '.installed-x86_64-linux-native' failed
make[2]: *** [.installed-x86_64-linux-native] Error 1
make[2]: Leaving directory '/root/kodi/tools/depends/native/distribute'
Makefile:61: recipe for target 'distribute' failed
make[1]: *** [distribute] Error 2

How Has This Been Tested?

This change will be tested by the automatic Jenkins build jobs.

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[lrusak]

Thanks for your contribution!