Remove sphinx_config.init_values() manual call

The function signature for Sphinx's config.init_values() changed since
version 1.3. That leads to:

TypeError: init_values() takes exactly 2 arguments (1 given)

But the function is already correctly called from
application.Sphinx()'s constructor. So use the configuration object
from the application instead of creating an own config object.

Change-Id: I343c26560bfe5116d5348b50b1890b3442ed845a
Closes-Bug: #1379998

pbr/builddoc.py

@@ -26,7 +26,6 @@ except ImportError:
 try:
     from sphinx import apidoc
     from sphinx import application
-    from sphinx import config
     from sphinx import setup_command
 except Exception as e:
     # NOTE(dhellmann): During the installation of docutils, setuptools
@@ -126,16 +125,16 @@ class LocalBuildDoc(setup_command.BuildDoc):
             confoverrides['release'] = self.release
         if self.today:
             confoverrides['today'] = self.today
-        sphinx_config = config.Config(self.config_dir, 'conf.py', {}, [])
-        sphinx_config.init_values()
-        if self.builder == 'man' and len(sphinx_config.man_pages) == 0:
-            return
+
         app = application.Sphinx(
             self.source_dir, self.config_dir,
             self.builder_target_dir, self.doctree_dir,
             self.builder, confoverrides, status_stream,
             freshenv=self.fresh_env, warningiserror=True)
 
+        if self.builder == 'man' and len(app.config.man_pages) == 0:
+            return
+
         try:
             app.build(force_all=self.all_files)
         except Exception as err: