Remove broken distutils compat

The distutils compat might be meaningful if the code did not
unconditionally call find_packages() (which is undefined in that
branch).  That said, there's probably no reason whatever why this
package would need such compat (i.e. be installed before setuptools),
so let's just drop it.

Author: mgorny

setup.py

@@ -1,12 +1,6 @@
 import codecs
-try:
-    from setuptools import setup, find_packages
-    extra_setup = dict(
-        install_requires=['requests', 'Jinja2>=2.9'],
-    )
-except ImportError:
-    from distutils.core import setup
-    extra_setup = {}
+
+from setuptools import setup, find_packages
 
 setup(
     name='readthedocs-sphinx-ext',
@@ -16,6 +10,7 @@
     url='http://github.com/readthedocs/readthedocs-sphinx-ext',
     license='MIT',
     description='Sphinx extension for Read the Docs overrides',
+    install_requires=['requests', 'Jinja2>=2.9'],
     package_dir={'': '.'},
     packages=find_packages('.'),
     long_description=codecs.open("README.rst", "r", "utf-8").read(),
@@ -24,5 +19,4 @@
     package_data={
         '': ['_static/*.js', '_static/*.js_t', '_static/*.css', '_templates/*.tmpl'],
     },
-    **extra_setup
 )