Remove duplicate build_ext class and get_ext_filename method

python/setup.py

@@ -157,21 +157,6 @@ class build_py(_build_py):
     return [(pkg, mod, fil) for (pkg, mod, fil) in modules
             if not any(fnmatch.fnmatchcase(fil, pat=pat) for pat in exclude)]
 
-class build_ext(_build_ext):
-  def get_ext_filename(self, ext_name):
-      # since python3.5, python extensions' shared libraries use a suffix that corresponds to the value
-      # of sysconfig.get_config_var('EXT_SUFFIX') and contains info about the architecture the library targets.
-      # E.g. on x64 linux the suffix is ".cpython-XYZ-x86_64-linux-gnu.so"
-      # When crosscompiling python wheels, we need to be able to override this suffix
-      # so that the resulting file name matches the target architecture and we end up with a well-formed
-      # wheel.
-      filename = _build_ext.get_ext_filename(self, ext_name)
-      orig_ext_suffix = sysconfig.get_config_var("EXT_SUFFIX")
-      new_ext_suffix = os.getenv("PROTOCOL_BUFFERS_OVERRIDE_EXT_SUFFIX")
-      if new_ext_suffix and filename.endswith(orig_ext_suffix):
-        filename = filename[:-len(orig_ext_suffix)] + new_ext_suffix
-      return filename
-
 class build_ext(_build_ext):
 
   def get_ext_filename(self, ext_name):