Revert "ob-C: Provide `ob-C++' and `ob-D'"

This reverts commit f35994b3147e9a086681197943d3fe661b122c25.

lisp/ob-C.el

@@ -463,7 +463,5 @@ specifying a variable with the name of the table."
 	 table table table))))))
 
 (provide 'ob-C)
-(provide 'ob-C++)
-(provide 'ob-D)
 
 ;;; ob-C.el ends here