Remove use of os.fchdir

- fchdir is not portable to Windows, trying to import it caused
  an error

Author: equalsraf

neovim/api/nvim.py

@@ -15,7 +15,6 @@
 
 
 os_chdir = os.chdir
-os_fchdir = os.fchdir
 
 
 class Nvim(object):
@@ -152,11 +151,6 @@ def chdir(self, dir_path):
         os_chdir(dir_path)
         return self._session.request('vim_change_directory', dir_path)
 
-    def fchdir(self, dir_fd):
-        """Run os.chdir, then all appropriate vim stuff."""
-        os_fchdir(dir_fd)
-        return self._session.request('vim_change_directory', os.getcwd())
-
     def feedkeys(self, keys, options='', escape_csi=True):
         """Push `keys` to Nvim user input buffer.