/*
 *  call-seq:
 *     dvector.reject! {|x| block }  -> dvector or nil
 *  
 *  Equivalent to <code>Dvector#delete_if</code>, deleting elements from
 *  _dvector_ for which the block evaluates to true, but returns
 *  <code>nil</code> if no changes were made. Also see
 *  <code>Enumerable#reject</code>.
 */ 
VALUE dvector_reject_bang(VALUE ary) {