Revert "bpo-26317: Support OBJC and OBJCXX configure command line variables (GH-20176)" (GH-20182)

This reverts commit 0da5466650.

The commit is causing make failures on a FreeBSD buildbot.
Due to the imminent 3.9.0b1 cutoff, revert this commit for
now pending further investigation.

setup.py

@@ -1583,11 +1583,10 @@ class PyBuildExt(build_ext):
             self.missing.append('ossaudiodev')
 
         if MACOS:
-            self.add(Extension('_scproxy', [],
+            self.add(Extension('_scproxy', ['_scproxy.c'],
                                extra_link_args=[
                                    '-framework', 'SystemConfiguration',
-                                   '-framework', 'CoreFoundation'],
-                               extra_objects=['Modules/_scproxy.o']))
+                                   '-framework', 'CoreFoundation']))
 
     def detect_compress_exts(self):
         # Andrew Kuchling's zlib module.  Note that some versions of zlib